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VINUM(8)                FreeBSD System Manager's Manual               VINUM(8)

NAME
     vinum -- Logical Volume Manager control program

SYNOPSIS
     vinum [command] [-options]

COMMANDS
     attach plex volume [rename]

     attach subdisk plex [offset] [rename]
             Attach a plex to a volume, or a subdisk to a plex.

     checkparity plex [-f] [-v]
             Check the parity blocks of a RAID-4 or RAID-5 plex.

     concat [-f] [-n name] [-v] drives
             Create a concatenated volume from the specified drives.

     create [-f] description-file
             Create a volume as described in description-file.

     debug   Cause the volume manager to enter the kernel debugger.

     debug flags
             Set debugging flags.

     detach [-f] [plex | subdisk]
             Detach a plex or subdisk from the volume or plex to which it is
             attached.

     dumpconfig [drive ...]
             List the configuration information stored on the specified
             drives, or all drives in the system if no drive names are speci-
             fied.

     info [-v] [-V]
             List information about volume manager state.

     init [-S size] [-w] plex | subdisk
             Initialize the contents of a subdisk or all the subdisks of a
             plex to all zeros.

     label volume
             Create a volume label.

     l | list [-r] [-s] [-v] [-V] [volume | plex | subdisk]
             List information about specified objects.

     ld [-r] [-s] [-v] [-V] [volume]
             List information about drives.

     ls [-r] [-s] [-v] [-V] [subdisk]
             List information about subdisks.

     lp [-r] [-s] [-v] [-V] [plex]
             List information about plexes.

     lv [-r] [-s] [-v] [-V] [volume]
             List information about volumes.

     makedev
             Remake the device nodes in /dev/vinum.

     mirror [-f] [-n name] [-s] [-v] drives
             Create a mirrored volume from the specified drives.

     move | mv -f drive object ...
             Move the object(s) to the specified drive.

     printconfig [file]
             Write a copy of the current configuration to file.

     quit    Exit the vinum program when running in interactive mode.  Nor-
             mally this would be done by entering the EOF character.

     read disk ...
             Read the vinum configuration from the specified disks.

     rename [-r] [drive | subdisk | plex | volume] newname
             Change the name of the specified object.

     rebuildparity plex [-f] [-v] [-V]
             Rebuild the parity blocks of a RAID-4 or RAID-5 plex.

     resetconfig
             Reset the complete vinum configuration.

     resetstats [-r] [volume | plex | subdisk]
             Reset statistics counters for the specified objects, or for all
             objects if none are specified.

     rm [-f] [-r] volume | plex | subdisk
             Remove an object.

     saveconfig
             Save vinum configuration to disk after configuration failures.

     setdaemon [value]
             Set daemon configuration.

     setstate state [volume | plex | subdisk | drive]
             Set state without influencing other objects, for diagnostic pur-
             poses only.

     start   Read configuration from all vinum drives.

     start [-i interval] [-S size] [-w] volume | plex | subdisk
             Allow the system to access the objects.

     stop [-f] [volume | plex | subdisk]
             Terminate access to the objects, or stop vinum if no parameters
             are specified.

     stripe [-f] [-n name] [-v] drives
             Create a striped volume from the specified drives.

DESCRIPTION
     vinum is a utility program to communicate with the vinum(4) logical vol-
     ume manager.  vinum is designed either for interactive use, when started
     without command line arguments, or to execute a single command if the
     command is supplied on the command line.  In interactive mode, vinum
     maintains a command line history.

OPTIONS
     vinum commands may optionally be followed by an option.  Any of the fol-
     lowing options may be specified with any command, but in some cases the
     options are ignored.  For example, the stop command ignores the -v and -V
     options.

     -f      The -f (``force'') option overrides safety checks.  Use with
             extreme care.  This option is for emergency use only.  For exam-
             ple, the command

                   rm -f myvolume

             removes myvolume even if it is open.  Any subsequent access to
             the volume will almost certainly cause a panic.

     -i millisecs
             When performing the init and start commands, wait millisecs mil-
             liseconds between copying each block.  This lowers the load on
             the system.

     -n name
             Use the -n option to specify a volume name to the simplified con-
             figuration commands concat, mirror and stripe.

     -r      The -r (``recursive'') option is used by the list commands to
             display information not only about the specified objects, but
             also about subordinate objects.  For example, in conjunction with
             the lv command, the -r option will also show information about
             the plexes and subdisks belonging to the volume.

     -s      The -s (``statistics'') option is used by the list commands to
             display statistical information.  The mirror command also uses
             this option to specify that it should create striped plexes.

     -S size
             The -S option specifies the transfer size for the init and start
             commands.

     -v      The -v (``verbose'') option can be used to request more detailed
             information.

     -V      The -V (``Very verbose'') option can be used to request more
             detailed information than the -v option provides.

     -w      The -w (``wait'') option tells vinum to wait for completion of
             commands which normally run in the background, such as init.

COMMANDS IN DETAIL
     vinum commands perform the following functions:

     attach plex volume [rename]
     attach subdisk plex [offset] [rename]
             vinum attach inserts the specified plex or subdisk in a volume or
             plex.  In the case of a subdisk, an offset in the plex may be
             specified.  If it is not, the subdisk will be attached at the
             first possible location.  After attaching a plex to a non-empty
             volume, vinum reintegrates the plex.

             If the keyword rename is specified, vinum renames the object (and
             in the case of a plex, any subordinate subdisks) to fit in with
             the default vinum naming convention.  To rename the object to any
             other name, use the rename command.

             A number of considerations apply to attaching subdisks:

             +o   Subdisks can normally only be attached to concatenated
                 plexes.

             +o   If a striped or RAID-5 plex is missing a subdisk (for example
                 after drive failure), it should be replaced by a subdisk of
                 the same size only.

             +o   In order to add further subdisks to a striped or RAID-5 plex,
                 use the -f (force) option.  This will corrupt the data in the
                 plex.

             +o   For concatenated plexes, the offset parameter specifies the
                 offset in blocks from the beginning of the plex.  For striped
                 and RAID-5 plexes, it specifies the offset of the first block
                 of the subdisk: in other words, the offset is the numerical
                 position of the subdisk multiplied by the stripe size.  For
                 example, in a plex with stripe size 271k, the first subdisk
                 will have offset 0, the second offset 271k, the third 542k,
                 etc.  This calculation ignores parity blocks in RAID-5
                 plexes.

     checkparity plex [-f] [-v]
             Check the parity blocks on the specified RAID-4 or RAID-5 plex.
             This operation maintains a pointer in the plex, so it can be
             stopped and later restarted from the same position if desired.
             In addition, this pointer is used by the rebuildparity command,
             so rebuilding the parity blocks need only start at the location
             where the first parity problem has been detected.

             If the -f flag is specified, checkparity starts checking at the
             beginning of the plex.  If the -v flag is specified, checkparity
             prints a running progress report.

     concat [-f] [-n name] [-v] drives
             The concat command provides a simplified alternative to the
             create command for creating volumes with a single concatenated
             plex.  The largest contiguous space available on each drive is
             used to create the subdisks for the plexes.

             Normally, the concat command creates an arbitrary name for the
             volume and its components.  The name is composed of the text
             ``vinum'' and a small integer, for example ``vinum3''.  You can
             override this with the -n name option, which assigns the name
             specified to the volume.  The plexes and subdisks are named after
             the volume in the default manner.

             There is no choice of name for the drives.  If the drives have
             already been initialized as vinum drives, the name remains.  Oth-
             erwise the drives are given names starting with the text
             ``vinumdrive'' and a small integer, for example ``vinumdrive7''.
             As with the create command, the -f option can be used to specify
             that a previous name should be overwritten.  The -v is used to
             specify verbose output.

             See the section SIMPLIFIED CONFIGURATION below for some examples
             of this command.

     create [-f] description-file
             vinum create is used to create any object.  In view of the rela-
             tively complicated relationship and the potential dangers
             involved in creating a vinum object, there is no interactive
             interface to this function.  If you do not specify a file name,
             vinum starts an editor on a temporary file.  If the environment
             variable EDITOR is set, vinum starts this editor.  If not, it
             defaults to vi.  See the section CONFIGURATION FILE below for
             more information on the format of this file.

             Note that the vinum create function is additive: if you run it
             multiple times, you will create multiple copies of all unnamed
             objects.

             Normally the create command will not change the names of existing
             vinum drives, in order to avoid accidentally erasing them.  The
             correct way to dispose of no longer wanted vinum drives is to
             reset the configuration with the resetconfig command.  In some
             cases, however, it may be necessary to create new data on vinum
             drives which can no longer be started.  In this case, use the
             create -f command.

     debug   vinum debug, without any arguments, is used to enter the remote
             kernel debugger.  It is only activated if vinum is built with the
             VINUMDEBUG option.  This option will stop the execution of the
             operating system until the kernel debugger is exited.  If remote
             debugging is set and there is no remote connection for a kernel
             debugger, it will be necessary to reset the system and reboot in
             order to leave the debugger.

     debug flags
             Set a bit mask of internal debugging flags.  These will change
             without warning as the product matures; to be certain, read the
             header file <sys/dev/vinumvar.h>.  The bit mask is composed of
             the following values:

             DEBUG_ADDRESSES (1)
                     Show buffer information during requests

             DEBUG_RESID (4)
                     Go into debugger in complete_rqe().

             DEBUG_LASTREQS (8)
                     Keep a circular buffer of last requests.

             DEBUG_REVIVECONFLICT (16)
                     Print info about revive conflicts.

             DEBUG_EOFINFO (32)
                     Print information about internal state when returning an
                     EOF on a striped plex.

             DEBUG_MEMFREE (64)
                     Maintain a circular list of the last memory areas freed
                     by the memory allocator.

             DEBUG_REMOTEGDB (256)
                     Go into remote gdb when the debug command is issued.

             DEBUG_WARNINGS (512)
                     Print some warnings about minor problems in the implemen-
                     tation.

     detach [-f] plex
     detach [-f] subdisk
             vinum detach removes the specified plex or subdisk from the vol-
             ume or plex to which it is attached.  If removing the object
             would impair the data integrity of the volume, the operation will
             fail unless the -f option is specified.  If the object is named
             after the object above it (for example, subdisk vol1.p7.s0
             attached to plex vol1.p7), the name will be changed by prepending
             the text ``ex-'' (for example, ex-vol1.p7.s0).  If necessary, the
             name will be truncated in the process.

             detach does not reduce the number of subdisks in a striped or
             RAID-5 plex.  Instead, the subdisk is marked absent, and can
             later be replaced with the attach command.

     dumpconfig [drive ...]

             vinum dumpconfig shows the configuration information stored on
             the specified drives.  If no drive names are specified,
             dumpconfig searches all drives on the system for Vinum partitions
             and dumps the information.  If configuration updates are dis-
             abled, it is possible that this information is not the same as
             the information returned by the list command.  This command is
             used primarily for maintenance and debugging.

     info    vinum info displays information about vinum memory usage.  This
             is intended primarily for debugging.  With the -v option, it will
             give detailed information about the memory areas in use.

             With the -V option, info displays information about the last up
             to 64 I/O requests handled by the vinum driver.  This information
             is only collected if debug flag 8 is set.  The format looks like:

             vinum -> info -V
             Flags: 0x200    1 opens
             Total of 38 blocks malloced, total memory: 16460
             Maximum allocs:       56, malloc table at 0xf0f72dbc

             Time             Event       Buf        Dev     Offset          Bytes   SD      SDoff   Doffset Goffset

             14:40:00.637758 1VS Write 0xf2361f40    91.3  0x10            16384
             14:40:00.639280 2LR Write 0xf2361f40    91.3  0x10            16384
             14:40:00.639294 3RQ Read  0xf2361f40    4.39   0x104109        8192    19      0       0       0
             14:40:00.639455 3RQ Read  0xf2361f40    4.23   0xd2109         8192    17      0       0       0
             14:40:00.639529 3RQ Read  0xf2361f40    4.15   0x6e109         8192    16      0       0       0
             14:40:00.652978 4DN Read  0xf2361f40    4.39   0x104109        8192    19      0       0       0
             14:40:00.667040 4DN Read  0xf2361f40    4.15   0x6e109         8192    16      0       0       0
             14:40:00.668556 4DN Read  0xf2361f40    4.23   0xd2109         8192    17      0       0       0
             14:40:00.669777 6RP Write 0xf2361f40    4.39   0x104109        8192    19      0       0       0
             14:40:00.685547 4DN Write 0xf2361f40    4.39   0x104109        8192    19      0       0       0
             11:11:14.975184 Lock      0xc2374210    2      0x1f8001
             11:11:15.018400 7VS Write 0xc2374210           0x7c0           32768   10
             11:11:15.018456 8LR Write 0xc2374210    13.39  0xcc0c9         32768
             11:11:15.046229 Unlock    0xc2374210    2      0x1f8001

             The Buf field always contains the address of the user buffer
             header.  This can be used to identify the requests associated
             with a user request, though this is not 100% reliable: theoreti-
             cally two requests in sequence could use the same buffer header,
             though this is not common.  The beginning of a request can be
             identified by the event 1VS or 7VS.  The first example above
             shows the requests involved in a user request.  The second is a
             subdisk I/O request with locking.

             The Event field contains information related to the sequence of
             events in the request chain.  The digit 1 to 6 indicates the
             approximate sequence of events, and the two-letter abbreviation
             is a mnemonic for the location:

             1VS       (vinumstrategy) shows information about the user
                       request on entry to vinumstrategy().  The device number
                       is the vinum device, and offset and length are the user
                       parameters.  This is always the beginning of a request
                       sequence.

             2LR       (launch_requests) shows the user request just prior to
                       launching the low-level vinum requests in the function
                       launch_requests().  The parameters should be the same
                       as in the 1VS information.

             In the following requests, Dev is the device number of the asso-
             ciated disk partition, Offset is the offset from the beginning of
             the partition, SD is the subdisk index in vinum_conf, SDoff is
             the offset from the beginning of the subdisk, Doffset is the off-
             set of the associated data request, and Goffset is the offset of
             the associated group request, where applicable.

             3RQ       (request) shows one of possibly several low-level vinum
                       requests which are launched to satisfy the high-level
                       request.  This information is also logged in
                       launch_requests().

             4DN       (done) is called from complete_rqe(), showing the com-
                       pletion of a request.  This completion should match a
                       request launched either at stage 4DN from
                       launch_requests(), or from complete_raid5_write() at
                       stage 5RD or 6RP.

             5RD       (RAID-5 data) is called from complete_raid5_write() and
                       represents the data written to a RAID-5 data stripe
                       after calculating parity.

             6RP       (RAID-5 parity) is called from complete_raid5_write()
                       and represents the data written to a RAID-5 parity
                       stripe after calculating parity.

             7VS       shows a subdisk I/O request.  These requests are usu-
                       ally internal to vinum for operations like initializa-
                       tion or rebuilding plexes.

             8LR       shows the low-level operation generated for a subdisk
                       I/O request.

             Lockwait  specifies that the process is waiting for a range lock.
                       The parameters are the buffer header associated with
                       the request, the plex number and the block number.  For
                       internal reasons the block number is one higher than
                       the address of the beginning of the stripe.

             Lock      specifies that a range lock has been obtained.  The
                       parameters are the same as for the range lock.

             Unlock    specifies that a range lock has been released.  The
                       parameters are the same as for the range lock.

     init [-S size] [-w] plex | subdisk
             vinum init initializes a subdisk by writing zeroes to it.  You
             can initialize all subdisks in a plex by specifying the plex
             name.  This is the only way to ensure consistent data in a plex.
             You must perform this initialization before using a RAID-5 plex.
             It is also recommended for other new plexes.  vinum initializes
             all subdisks of a plex in parallel.  Since this operation can
             take a long time, it is normally performed in the background.  If
             you want to wait for completion of the command, use the -w (wait)
             option.

             Specify the -S option if you want to write blocks of a different
             size from the default value of 16 kB.  vinum prints a console
             message when the initialization is complete.

     label volume
             The label command writes a ufs style volume label on a volume.
             It is a simple alternative to an appropriate call to disklabel.
             This is needed because some ufs commands still read the disk to
             find the label instead of using the correct ioctl(2) call to
             access it.  vinum maintains a volume label separately from the
             volume data, so this command is not needed for newfs(8).  This
             command is deprecated.

     list [-r] [-V] [volume | plex | subdisk]
     l [-r] [-V] [volume | plex | subdisk]
     ld [-r] [-s] [-v] [-V] [volume]
     ls [-r] [-s] [-v] [-V] [subdisk]
     lp [-r] [-s] [-v] [-V] [plex]
     lv [-r] [-s] [-v] [-V] [volume]
             list is used to show information about the specified object.  If
             the argument is omitted, information is shown about all objects
             known to vinum.  The l command is a synonym for list.

             The -r option relates to volumes and plexes: if specified, it
             recursively lists information for the subdisks and (for a volume)
             plexes subordinate to the objects.  The commands lv, lp, ls and
             ld list only volumes, plexes, subdisks and drives respectively.
             This is particularly useful when used without parameters.

             The -s option causes vinum to output device statistics, the -v
             (verbose) option causes some additional information to be output,
             and the -V causes considerable additional information to be out-
             put.

     makedev
             The makedev command removes the directory /dev/vinum and recre-
             ates it with device nodes which reflect the current configura-
             tion.  This command is not intended for general use, and is pro-
             vided for emergency use only.

     mirror [-f] [-n name] [-s] [-v] drives
             The mirror command provides a simplified alternative to the
             create command for creating mirrored volumes.  Without any
             options, it creates a RAID-1 (mirrored) volume with two concate-
             nated plexes.  The largest contiguous space available on each
             drive is used to create the subdisks for the plexes.  The first
             plex is built from the odd-numbered drives in the list, and the
             second plex is built from the even-numbered drives.  If the
             drives are of different sizes, the plexes will be of different
             sizes.

             If the -s option is provided, mirror builds striped plexes with a
             stripe size of 256 kB.  The size of the subdisks in each plex is
             the size of the smallest contiguous storage available on any of
             the drives which form the plex.  Again, the plexes may differ in
             size.

             Normally, the mirror command creates an arbitrary name for the
             volume and its components.  The name is composed of the text
             ``vinum'' and a small integer, for example ``vinum3''.  You can
             override this with the -n name option, which assigns the name
             specified to the volume.  The plexes and subdisks are named after
             the volume in the default manner.

             There is no choice of name for the drives.  If the drives have
             already been initialized as vinum drives, the name remains.  Oth-
             erwise the drives are given names starting with the text
             ``vinumdrive'' and a small integer, for example ``vinumdrive7''.
             As with the create command, the -f option can be used to specify
             that a previous name should be overwritten.  The -v is used to
             specify verbose output.

             See the section SIMPLIFIED CONFIGURATION below for some examples
             of this command.

     mv -f drive object ...
     move -f drive object ...
             Move all the subdisks from the specified objects onto the new
             drive.  The objects may be subdisks, drives or plexes.  When
             drives or plexes are specified, all subdisks associated with the
             object are moved.

             The -f option is required for this function, since it currently
             does not preserve the data in the subdisk.  This functionality
             will be added at a later date.  In this form, however, it is
             suited to recovering a failed disk drive.

     printconfig [file]
             Write a copy of the current configuration to file in a format
             that can be used to recreate the vinum configuration.  Unlike the
             configuration saved on disk, it includes definitions of the
             drives.  If you omit file, vinum writes the list to stdout.

     quit    Exit the vinum program when running in interactive mode.  Nor-
             mally this would be done by entering the EOF character.

     read disk ...
             The read command scans the specified disks for vinum partitions
             containing previously created configuration information.  It
             reads the configuration in order from the most recently updated
             to least recently updated configuration.  vinum maintains an up-
             to-date copy of all configuration information on each disk parti-
             tion.  You must specify all of the slices in a configuration as
             the parameter to this command.

             The read command is intended to selectively load a vinum configu-
             ration on a system which has other vinum partitions.  If you want
             to start all partitions on the system, it is easier to use the
             start command.

             If vinum encounters any errors during this command, it will turn
             off automatic configuration update to avoid corrupting the copies
             on disk.  This will also happen if the configuration on disk
             indicates a configuration error (for example, subdisks which do
             not have a valid space specification).  You can turn the updates
             on again with the setdaemon and saveconfig commands.  Reset bit 2
             (numerical value 4) of the daemon options mask to re-enable con-
             figuration saves.

     rebuildparity plex [-f] [-v] [-V]
             Rebuild the parity blocks on the specified RAID-4 or RAID-5 plex.
             This operation maintains a pointer in the plex, so it can be
             stopped and later restarted from the same position if desired.
             In addition, this pointer is used by the checkparity command, so
             rebuilding the parity blocks need only start at the location
             where the first parity problem has been detected.

             If the -f flag is specified, rebuildparity starts rebuilding at
             the beginning of the plex.  If the -v flag is specified,
             rebuildparity first checks the existing parity blocks prints
             information about those found to be incorrect before rebuilding.
             If the -V flag is specified, rebuildparity prints a running
             progress report.

     rename [-r] [drive | subdisk | plex | volume] newname
             Change the name of the specified object.  If the -r option is
             specified, subordinate objects will be named by the default
             rules: plex names will be formed by appending .pnumber to the
             volume name, and subdisk names will be formed by appending
             .snumber to the plex name.

     resetconfig
             The resetconfig command completely obliterates the vinum configu-
             ration on a system.  Use this command only when you want to com-
             pletely delete the configuration.  vinum will ask for confirma-
             tion; you must type in the words NO FUTURE exactly as shown:

                   # vinum resetconfig

                   WARNING!  This command will completely wipe out your vinum
                   configuration.  All data will be lost.  If you really want
                   to do this, enter the text

                   NO FUTURE
                   Enter text -> NO FUTURE
                   Vinum configuration obliterated

             As the message suggests, this is a last-ditch command.  Don't use
             it unless you have an existing configuration which you never want
             to see again.

     resetstats [-r] [volume | plex | subdisk]
             vinum maintains a number of statistical counters for each object.
             See the header file <sys/dev/vinumvar.h> for more information.
             Use the resetstats command to reset these counters.  In conjunc-
             tion with the -r option, vinum also resets the counters of subor-
             dinate objects.

     rm [-f] [-r] volume | plex | subdisk
             rm removes an object from the vinum configuration.  Once an
             object has been removed, there is no way to recover it.  Normally
             vinum performs a large amount of consistency checking before
             removing an object.  The -f option tells vinum to omit this
             checking and remove the object anyway.  Use this option with
             great care: it can result in total loss of data on a volume.

             Normally, vinum refuses to remove a volume or plex if it has sub-
             ordinate plexes or subdisks respectively.  You can tell vinum to
             remove the object anyway by using the -f option, or you can cause
             vinum to remove the subordinate objects as well by using the -r
             (recursive) option.  If you remove a volume with the -r option,
             it will remove both the plexes and the subdisks which belong to
             the plexes.

     saveconfig
             Save the current configuration to disk.  Normally this is not
             necessary, since vinum automatically saves any change in configu-
             ration.  If an error occurs on startup, updates will be disabled.
             When you reenable them with the setdaemon command, vinum does not
             automatically save the configuration to disk.  Use this command
             to save the configuration.

     setdaemon [value]
             setdaemon sets a variable bitmask for the vinum daemon.  This
             command is temporary and will be replaced.  Currently, the bit
             mask may contain the bits 1 (log every action to syslog) and 4
             (don't update configuration).  Option bit 4 can be useful for
             error recovery.

     setstate state [volume | plex | subdisk | drive]
             setstate sets the state of the specified objects to the specified
             state.  This bypasses the usual consistency mechanism of vinum
             and should be used only for recovery purposes.  It is possible to
             crash the system by incorrect use of this command.

     start [-i interval] [-S size] [-w] [plex | subdisk]
             start starts (brings into to the up state) one or more vinum
             objects.

             If no object names are specified, vinum scans the disks known to
             the system for vinum drives and then reads in the configuration
             as described under the read commands.  The vinum drive contains a
             header with all information about the data stored on the drive,
             including the names of the other drives which are required in
             order to represent plexes and volumes.

             If vinum encounters any errors during this command, it will turn
             off automatic configuration update to avoid corrupting the copies
             on disk.  This will also happen if the configuration on disk
             indicates a configuration error (for example, subdisks which do
             not have a valid space specification).  You can turn the updates
             on again with the setdaemon and saveconfig command.  Reset bit 4
             of the daemon options mask to re-enable configuration saves.

             If object names are specified, vinum starts them.  Normally this
             operation is only of use with subdisks.  The action depends on
             the current state of the object:

             +o   If the object is already in the up state, vinum does nothing.

             +o   If the object is a subdisk in the down or reborn states,
                 vinum changes it to the up state.

             +o   If the object is a subdisk in the empty state, the change
                 depends on the subdisk.  If it is part of a plex which is
                 part of a volume which contains other plexes, vinum places
                 the subdisk in the reviving state and attempts to copy the
                 data from the volume.  When the operation completes, the sub-
                 disk is set into the up state.  If it is part of a plex which
                 is part of a volume which contains no other plexes, or if it
                 is not part of a plex, vinum brings it into the up state
                 immediately.

             +o   If the object is a subdisk in the reviving state, vinum con-
                 tinues the revive operation offline.  When the operation com-
                 pletes, the subdisk is set into the up state.

             When a subdisk comes into the up state, vinum automatically
             checks the state of any plex and volume to which it may belong
             and changes their state where appropriate.

             If the object is a plex, start checks the state of the subordi-
             nate subdisks (and plexes in the case of a volume) and starts any
             subdisks which can be started.

             To start a plex in a multi-plex volume, the data must be copied
             from another plex in the volume.  Since this frequently takes a
             long time, it is normally done in the background.  If you want to
             wait for this operation to complete (for example, if you are per-
             forming this operation in a script), use the -w option.

             Copying data doesn't just take a long time, it can also place a
             significant load on the system.  You can specify the transfer
             size in bytes or sectors with the -S option, and an interval (in
             milliseconds) to wait between copying each block with the -i
             option.  Both of these options lessen the load on the system.

     stop [-f] [volume | plex | subdisk]
             If no parameters are specified, stop removes the vinum KLD and
             stops vinum(4).  This can only be done if no objects are active.
             In particular, the -f option does not override this requirement.
             Normally, the stop command writes the current configuration back
             to the drives before terminating.  This will not be possible if
             configuration updates are disabled, so vinum will not stop if
             configuration updates are disabled.  You can override this by
             specifying the -f option.

             The stop command can only work if vinum has been loaded as a KLD,
             since it is not possible to unload a statically configured
             driver.  vinum stop will fail if vinum is statically configured.

             If object names are specified, stop disables access to the
             objects.  If the objects have subordinate objects, they subordi-
             nate objects must either already be inactive (stopped or in
             error), or the -r and -f options must be specified.  This command
             does not remove the objects from the configuration.  They can be
             accessed again after a start command.

             By default, vinum does not stop active objects.  For example, you
             cannot stop a plex which is attached to an active volume, and you
             cannot stop a volume which is open.  The -f option tells vinum to
             omit this checking and remove the object anyway.  Use this option
             with great care and understanding: used incorrectly, it can
             result in serious data corruption.

     stripe [-f] [-n name] [-v] drives
             The stripe command provides a simplified alternative to the
             create command for creating volumes with a single striped plex.
             The size of the subdisks is the size of the largest contiguous
             space available on all the specified drives.  The stripe size is
             fixed at 256 kB.

             Normally, the stripe command creates an arbitrary name for the
             volume and its components.  The name is composed of the text
             ``vinum'' and a small integer, for example ``vinum3''.  You can
             override this with the -n name option, which assigns the name
             specified to the volume.  The plexes and subdisks are named after
             the volume in the default manner.

             There is no choice of name for the drives.  If the drives have
             already been initialized as vinum drives, the name remains.  Oth-
             erwise the drives are given names starting with the text
             ``vinumdrive'' and a small integer, for example ``vinumdrive7''.
             As with the create command, the -f option can be used to specify
             that a previous name should be overwritten.  The -v is used to
             specify verbose output.

             See the section SIMPLIFIED CONFIGURATION below for some examples
             of this command.

SIMPLIFIED CONFIGURATION
     This section describes a simplified interface to vinum configuration
     using the concat, mirror and stripe commands.  These commands create con-
     venient configurations for some more normal situations, but they are not
     as flexible as the create command.

     See above for the description of the commands.  Here are some examples,
     all performed with the same collection of disks.  Note that the first
     drive, /dev/da1h, is smaller than the others.  This has an effect on the
     sizes chosen for each kind of subdisk.

     The following examples all use the -v option to show the commands passed
     to the system, and also to list the structure of the volume.  Without the
     -v option, these commands produce no output.

   Volume with a single concatenated plex
     Use a volume with a single concatenated plex for the largest possible
     storage without resilience to drive failures:

     vinum -> concat -v /dev/da1h /dev/da2h /dev/da3h /dev/da4h
     volume vinum0
       plex name vinum0.p0 org concat
     drive vinumdrive0 device /dev/da1h
         sd name vinum0.p0.s0 drive vinumdrive0 size 0
     drive vinumdrive1 device /dev/da2h
         sd name vinum0.p0.s1 drive vinumdrive1 size 0
     drive vinumdrive2 device /dev/da3h
         sd name vinum0.p0.s2 drive vinumdrive2 size 0
     drive vinumdrive3 device /dev/da4h
         sd name vinum0.p0.s3 drive vinumdrive3 size 0
     V vinum0                State: up       Plexes:       1 Size:       2134 MB
     P vinum0.p0           C State: up       Subdisks:     4 Size:       2134 MB
     S vinum0.p0.s0          State: up       PO:        0  B Size:        414 MB
     S vinum0.p0.s1          State: up       PO:      414 MB Size:        573 MB
     S vinum0.p0.s2          State: up       PO:      988 MB Size:        573 MB
     S vinum0.p0.s3          State: up       PO:     1561 MB Size:        573 MB

     In this case, the complete space on all four disks was used, giving a
     volume 2134 MB in size.

   Volume with a single striped plex
     A volume with a single striped plex may give better performance than a
     concatenated plex, but restrictions on striped plexes can mean that the
     volume is smaller.  It will also not be resilient to a drive failure:

     vinum -> stripe -v /dev/da1h /dev/da2h /dev/da3h /dev/da4h
     drive vinumdrive0 device /dev/da1h
     drive vinumdrive1 device /dev/da2h
     drive vinumdrive2 device /dev/da3h
     drive vinumdrive3 device /dev/da4h
     volume vinum0
       plex name vinum0.p0 org striped 256k
         sd name vinum0.p0.s0 drive vinumdrive0 size 849825b
         sd name vinum0.p0.s1 drive vinumdrive1 size 849825b
         sd name vinum0.p0.s2 drive vinumdrive2 size 849825b
         sd name vinum0.p0.s3 drive vinumdrive3 size 849825b
     V vinum0                State: up       Plexes:       1 Size:       1659 MB
     P vinum0.p0           S State: up       Subdisks:     4 Size:       1659 MB
     S vinum0.p0.s0          State: up       PO:        0  B Size:        414 MB
     S vinum0.p0.s1          State: up       PO:      256 kB Size:        414 MB
     S vinum0.p0.s2          State: up       PO:      512 kB Size:        414 MB
     S vinum0.p0.s3          State: up       PO:      768 kB Size:        414 MB

     In this case, the size of the subdisks has been limited to the smallest
     available disk, so the resulting volume is only 1659 MB in size.

   Mirrored volume with two concatenated plexes
     For more reliability, use a mirrored, concatenated volume:

     vinum -> mirror -v -n mirror /dev/da1h /dev/da2h /dev/da3h /dev/da4h
     drive vinumdrive0 device /dev/da1h
     drive vinumdrive1 device /dev/da2h
     drive vinumdrive2 device /dev/da3h
     drive vinumdrive3 device /dev/da4h
     volume mirror setupstate
       plex name mirror.p0 org concat
         sd name mirror.p0.s0 drive vinumdrive0 size 0b
         sd name mirror.p0.s1 drive vinumdrive2 size 0b
       plex name mirror.p1 org concat
         sd name mirror.p1.s0 drive vinumdrive1 size 0b
         sd name mirror.p1.s1 drive vinumdrive3 size 0b
     V mirror                State: up       Plexes:       2 Size:       1146 MB
     P mirror.p0           C State: up       Subdisks:     2 Size:        988 MB
     P mirror.p1           C State: up       Subdisks:     2 Size:       1146 MB
     S mirror.p0.s0          State: up       PO:        0  B Size:        414 MB
     S mirror.p0.s1          State: up       PO:      414 MB Size:        573 MB
     S mirror.p1.s0          State: up       PO:        0  B Size:        573 MB
     S mirror.p1.s1          State: up       PO:      573 MB Size:        573 MB

     This example specifies the name of the volume, mirror.  Since one drive
     is smaller than the others, the two plexes are of different size, and the
     last 158 MB of the volume is non-resilient.  To ensure complete reliabil-
     ity in such a situation, use the create command to create a volume with
     988 MB.

   Mirrored volume with two striped plexes
     Alternatively, use the -s option to create a mirrored volume with two
     striped plexes:

     vinum -> mirror -v -n raid10 -s /dev/da1h /dev/da2h /dev/da3h /dev/da4h
     drive vinumdrive0 device /dev/da1h
     drive vinumdrive1 device /dev/da2h
     drive vinumdrive2 device /dev/da3h
     drive vinumdrive3 device /dev/da4h
     volume raid10 setupstate
       plex name raid10.p0 org striped 256k
         sd name raid10.p0.s0 drive vinumdrive0 size 849825b
         sd name raid10.p0.s1 drive vinumdrive2 size 849825b
       plex name raid10.p1 org striped 256k
         sd name raid10.p1.s0 drive vinumdrive1 size 1173665b
         sd name raid10.p1.s1 drive vinumdrive3 size 1173665b
     V raid10                State: up       Plexes:       2 Size:       1146 MB
     P raid10.p0           S State: up       Subdisks:     2 Size:        829 MB
     P raid10.p1           S State: up       Subdisks:     2 Size:       1146 MB
     S raid10.p0.s0          State: up       PO:        0  B Size:        414 MB
     S raid10.p0.s1          State: up       PO:      256 kB Size:        414 MB
     S raid10.p1.s0          State: up       PO:        0  B Size:        573 MB
     S raid10.p1.s1          State: up       PO:      256 kB Size:        573 MB

     In this case, the usable part of the volume is even smaller, since the
     first plex has shrunken to match the smallest drive.

CONFIGURATION FILE
     vinum requires that all parameters to the create commands must be in a
     configuration file.  Entries in the configuration file define volumes,
     plexes and subdisks, and may be in free format, except that each entry
     must be on a single line.

   Scale factors
     Some configuration file parameters specify a size (lengths, stripe
     sizes).  These values can be specified as bytes, or one of the following
     scale factors may be appended:

     s       specifies that the value is a number of sectors of 512 bytes.

     k       specifies that the value is a number of kilobytes (1024 bytes).

     m       specifies that the value is a number of megabytes (1048576
             bytes).

     g       specifies that the value is a number of gigabytes (1073741824
             bytes).

     b       is used for compatibility with VERITAS.  It stands for blocks of
             512 bytes.  This abbreviation is confusing, since the word
             ``block'' is used in different meanings, and its use is depre-
             cated.

     For example, the value 16777216 bytes can also be written as 16m, 16384k
     or 32768s.

     The configuration file can contain the following entries:

     drive name devicename [options]
           Define a drive.  The options are:

           device devicename   Specify the device on which the drive resides.
                               devicename must be the name of a disk parti-
                               tion, for example /dev/da1e or /dev/ad3s2h, and
                               it must be of type vinum.  Do not use the ``c''
                               partition, which is reserved for the complete
                               disk.

           hotspare            Define the drive to be a ``hot spare'' drive,
                               which is maintained to automatically replace a
                               failed drive.  vinum does not allow this drive
                               to be used for any other purpose.  In particu-
                               lar, it is not possible to create subdisks on
                               it.  This functionality has not been completely
                               implemented.

     volume name [options]
           Define a volume with name name.  Options are:

           plex plexname       Add the specified plex to the volume.  If
                               plexname is specified as *, vinum will look for
                               the definition of the plex as the next possible
                               entry in the configuration file after the defi-
                               nition of the volume.

           readpol policy      Define a read policy for the volume.  policy
                               may be either round or prefer plexname.  vinum
                               satisfies a read request from only one of the
                               plexes.  A round read policy specifies that
                               each read should be performed from a different
                               plex in round-robin fashion.  A prefer read
                               policy reads from the specified plex every
                               time.

           setupstate          When creating a multi-plex volume, assume that
                               the contents of all the plexes are consistent.
                               This is normally not the case, so by default
                               vinum sets all plexes except the first one to
                               the faulty state.  Use the start command to
                               first bring them to a consistent state.  In the
                               case of striped and concatenated plexes, how-
                               ever, it does not normally cause problems to
                               leave them inconsistent: when using a volume
                               for a file system or a swap partition, the pre-
                               vious contents of the disks are not of inter-
                               est, so they may be ignored.  If you want to
                               take this risk, use the setupstate keyword.  It
                               will only apply to the plexes defined immedi-
                               ately after the volume in the configuration
                               file.  If you add plexes to a volume at a later
                               time, you must integrate them manually with the
                               start command.

                               Note that you must use the init command with
                               RAID-5 plexes: otherwise extreme data corrup-
                               tion will result if one subdisk fails.

     plex [options]
           Define a plex.  Unlike a volume, a plex does not need a name.  The
           options may be:

           name plexname       Specify the name of the plex.  Note that you
                               must use the keyword name when naming a plex or
                               subdisk.

           org organization [stripesize]
                               Specify the organization of the plex.
                               organization can be one of concat, striped or
                               raid5.  For striped and raid5 plexes, the
                               parameter stripesize must be specified, while
                               for concat it must be omitted.  For type
                               striped, it specifies the width of each stripe.
                               For type raid5, it specifies the size of a
                               group.  A group is a portion of a plex which
                               stores the parity bits all in the same subdisk.
                               It must be a factor of the plex size (in other
                               words, the result of dividing the plex size by
                               the stripe size must be an integer), and it
                               must be a multiple of a disk sector (512
                               bytes).

                               For optimum performance, stripes should be at
                               least 128 kB in size: anything smaller will
                               result in a significant increase in I/O activ-
                               ity due to mapping of individual requests over
                               multiple disks.  The performance improvement
                               due to the increased number of concurrent
                               transfers caused by this mapping will not make
                               up for the performance drop due to the increase
                               in latency.  A good guideline for stripe size
                               is between 256 kB and 512 kB.  Avoid powers of
                               2, however: they tend to cause all superblocks
                               to be placed on the first subdisk.

                               A striped plex must have at least two subdisks
                               (otherwise it is a concatenated plex), and each
                               must be the same size.  A RAID-5 plex must have
                               at least three subdisks, and each must be the
                               same size.  In practice, a RAID-5 plex should
                               have at least 5 subdisks.

           volume volname      Add the plex to the specified volume.  If no
                               volume keyword is specified, the plex will be
                               added to the last volume mentioned in the con-
                               figuration file.

           sd sdname offset    Add the specified subdisk to the plex at offset
                               offset.

     subdisk [options]
           Define a subdisk.  Options may be:

           name name           Specify the name of a subdisk.  It is not nec-
                               essary to specify a name for a subdisk, see
                               OBJECT NAMING above.  Note that you must spec-
                               ify the keyword name if you wish to name a sub-
                               disk.

           plexoffset offset   Specify the starting offset of the subdisk in
                               the plex.  If not specified, vinum allocates
                               the space immediately after the previous sub-
                               disk, if any, or otherwise at the beginning of
                               the plex.

           driveoffset offset  Specify the starting offset of the subdisk in
                               the drive.  If not specified, vinum allocates
                               the first contiguous length bytes of free space
                               on the drive.

           length length       Specify the length of the subdisk.  This key-
                               word must be specified.  There is no default,
                               but the value 0 may be specified to mean ``use
                               the largest available contiguous free area on
                               the drive''.  If the drive is empty, this means
                               that the entire drive will be used for the sub-
                               disk.  length may be shortened to len.

           plex plex           Specify the plex to which the subdisk belongs.
                               By default, the subdisk belongs to the last
                               plex specified.

           drive drive         Specify the drive on which the subdisk resides.
                               By default, the subdisk resides on the last
                               drive specified.

EXAMPLE CONFIGURATION FILE
     # Sample vinum configuration file
     #
     # Our drives
     drive drive1 device /dev/da1h
     drive drive2 device /dev/da2h
     drive drive3 device /dev/da3h
     drive drive4 device /dev/da4h
     drive drive5 device /dev/da5h
     drive drive6 device /dev/da6h
     # A volume with one striped plex
     volume tinyvol
      plex org striped 512b
       sd length 64m drive drive2
       sd length 64m drive drive4
     volume stripe
      plex org striped 512b
       sd length 512m drive drive2
       sd length 512m drive drive4
     # Two plexes
     volume concat
      plex org concat
       sd length 100m drive drive2
       sd length 50m drive drive4
      plex org concat
       sd length 150m drive drive4
     # A volume with one striped plex and one concatenated plex
     volume strcon
      plex org striped 512b
       sd length 100m drive drive2
       sd length 100m drive drive4
      plex org concat
       sd length 150m drive drive2
       sd length 50m drive drive4
     # a volume with a RAID-5 and a striped plex
     # note that the RAID-5 volume is longer by
     # the length of one subdisk
     volume vol5
      plex org striped 64k
       sd length 1000m drive drive2
       sd length 1000m drive drive4
      plex org raid5 32k
       sd length 500m drive drive1
       sd length 500m drive drive2
       sd length 500m drive drive3
       sd length 500m drive drive4
       sd length 500m drive drive5

DRIVE LAYOUT CONSIDERATIONS
     vinum drives are currently BSD disk partitions.  They must be of type
     vinum in order to avoid overwriting data used for other purposes.  Use
     disklabel -e to edit a partition type definition.  The following display
     shows a typical partition layout as shown by disklabel(8):

     8 partitions:
     #        size   offset    fstype   [fsize bsize bps/cpg]
       a:    81920   344064    4.2BSD        0     0     0   # (Cyl.  240*- 297*)
       b:   262144    81920      swap                        # (Cyl.   57*- 240*)
       c:  4226725        0    unused        0     0         # (Cyl.    0 - 2955*)
       e:    81920        0    4.2BSD        0     0     0   # (Cyl.    0 - 57*)
       f:  1900000   425984    4.2BSD        0     0     0   # (Cyl.  297*- 1626*)
       g:  1900741  2325984     vinum        0     0     0   # (Cyl. 1626*- 2955*)

     In this example, partition ``g'' may be used as a vinum partition.  Par-
     titions ``a'', ``e'' and ``f'' may be used as UFS file systems or ccd
     partitions.  Partition ``b'' is a swap partition, and partition ``c''
     represents the whole disk and should not be used for any other purpose.

     vinum uses the first 265 sectors on each partition for configuration
     information, so the maximum size of a subdisk is 265 sectors smaller than
     the drive.

LOG FILE
     vinum maintains a log file, by default /var/tmp/vinum_history, in which
     it keeps track of the commands issued to vinum.  You can override the
     name of this file by setting the environment variable VINUM_HISTORY to
     the name of the file.

     Each message in the log file is preceded by a date.  The default format
     is "%e %b %Y %H:%M:%S".  See strftime(3) for further details of the for-
     mat string.  It can be overridden by the environment variable
     VINUM_DATEFORMAT.

HOW TO SET UP VINUM
     This section gives practical advice about how to implement a vinum sys-
     tem.

   Where to put the data
     The first choice you need to make is where to put the data.  You need
     dedicated disk partitions for vinum.  They should be partitions, not
     devices, and they should not be partition ``c''.  For example, good names
     are /dev/da0e or /dev/ad3s4a.  Bad names are /dev/da0 and /dev/da0s1,
     both of which represent a device, not a partition, and /dev/ad1c, which
     represents a complete disk and should be of type unused.  See the example
     under DRIVE LAYOUT CONSIDERATIONS above.

   Designing volumes
     The way you set up vinum volumes depends on your intentions.  There are a
     number of possibilities:

     1.   You may want to join up a number of small disks to make a reasonable
          sized file system.  For example, if you had five small drives and
          wanted to use all the space for a single volume, you might write a
          configuration file like:

                drive d1 device /dev/da2e
                drive d2 device /dev/da3e
                drive d3 device /dev/da4e
                drive d4 device /dev/da5e
                drive d5 device /dev/da6e
                volume bigger
                 plex org concat
                   sd length 0 drive d1
                   sd length 0 drive d2
                   sd length 0 drive d3
                   sd length 0 drive d4
                   sd length 0 drive d5

          In this case, you specify the length of the subdisks as 0, which
          means ``use the largest area of free space that you can find on the
          drive''.  If the subdisk is the only subdisk on the drive, it will
          use all available space.

     2.   You want to set up vinum to obtain additional resilience against
          disk failures.  You have the choice of RAID-1, also called
          ``mirroring'', or RAID-5, also called ``parity''.

          To set up mirroring, create multiple plexes in a volume.  For exam-
          ple, to create a mirrored volume of 2 GB, you might create the fol-
          lowing configuration file:

                drive d1 device /dev/da2e
                drive d2 device /dev/da3e
                volume mirror
                 plex org concat
                   sd length 2g drive d1
                 plex org concat
                   sd length 2g drive d2

          When creating mirrored drives, it is important to ensure that the
          data from each plex is on a different physical disk so that vinum
          can access the complete address space of the volume even if a drive
          fails.  Note that each plex requires as much data as the complete
          volume: in this example, the volume has a size of 2 GB, but each
          plex (and each subdisk) requires 2 GB, so the total disk storage
          requirement is 4 GB.

          To set up RAID-5, create a single plex of type raid5.  For example,
          to create an equivalent resilient volume of 2 GB, you might use the
          following configuration file:

                drive d1 device /dev/da2e
                drive d2 device /dev/da3e
                drive d3 device /dev/da4e
                drive d4 device /dev/da5e
                drive d5 device /dev/da6e
                volume raid
                 plex org raid5 512k
                   sd length 512m drive d1
                   sd length 512m drive d2
                   sd length 512m drive d3
                   sd length 512m drive d4
                   sd length 512m drive d5

          RAID-5 plexes require at least three subdisks, one of which is used
          for storing parity information and is lost for data storage.  The
          more disks you use, the greater the proportion of the disk storage
          can be used for data storage.  In this example, the total storage
          usage is 2.5 GB, compared to 4 GB for a mirrored configuration.  If
          you were to use the minimum of only three disks, you would require 3
          GB to store the information, for example:

                drive d1 device /dev/da2e
                drive d2 device /dev/da3e
                drive d3 device /dev/da4e
                volume raid
                 plex org raid5 512k
                   sd length 1g drive d1
                   sd length 1g drive d2
                   sd length 1g drive d3

          As with creating mirrored drives, it is important to ensure that the
          data from each subdisk is on a different physical disk so that vinum
          can access the complete address space of the volume even if a drive
          fails.

     3.   You want to set up vinum to allow more concurrent access to a file
          system.  In many cases, access to a file system is limited by the
          speed of the disk.  By spreading the volume across multiple disks,
          you can increase the throughput in multi-access environments.  This
          technique shows little or no performance improvement in single-
          access environments.  vinum uses a technique called ``striping'', or
          sometimes RAID-0, to increase this concurrency of access.  The name
          RAID-0 is misleading: striping does not provide any redundancy or
          additional reliability.  In fact, it decreases the reliability,
          since the failure of a single disk will render the volume useless,
          and the more disks you have, the more likely it is that one of them
          will fail.

          To implement striping, use a striped plex:

                drive d1 device /dev/da2e
                drive d2 device /dev/da3e
                drive d3 device /dev/da4e
                drive d4 device /dev/da5e
                volume raid
                 plex org striped 512k
                   sd length 512m drive d1
                   sd length 512m drive d2
                   sd length 512m drive d3
                   sd length 512m drive d4

          A striped plex must have at least two subdisks, but the increase in
          performance is greater if you have a larger number of disks.

     4.   You may want to have the best of both worlds and have both
          resilience and performance.  This is sometimes called RAID-10 (a
          combination of RAID-1 and RAID-0), though again this name is mis-
          leading.  With vinum you can do this with the following configura-
          tion file:

                drive d1 device /dev/da2e
                drive d2 device /dev/da3e
                drive d3 device /dev/da4e
                drive d4 device /dev/da5e
                volume raid setupstate
                 plex org striped 512k
                   sd length 512m drive d1
                   sd length 512m drive d2
                   sd length 512m drive d3
                   sd length 512m drive d4
                 plex org striped 512k
                   sd length 512m drive d4
                   sd length 512m drive d3
                   sd length 512m drive d2
                   sd length 512m drive d1

          Here the plexes are striped, increasing performance, and there are
          two of them, increasing reliability.  Note that this example shows
          the subdisks of the second plex in reverse order from the first
          plex.  This is for performance reasons and will be discussed below.
          In addition, the volume specification includes the keyword
          setupstate, which ensures that all plexes are up after creation.

   Creating the volumes
     Once you have created your configuration files, start vinum and create
     the volumes.  In this example, the configuration is in the file
     configfile:

       # vinum create -v configfile
          1: drive d1 device /dev/da2e
          2: drive d2 device /dev/da3e
          3: volume mirror
          4:  plex org concat
          5:    sd length 2g drive d1
          6:  plex org concat
          7:    sd length 2g drive d2
       Configuration summary

       Drives:         2 (4 configured)
       Volumes:        1 (4 configured)
       Plexes:         2 (8 configured)
       Subdisks:       2 (16 configured)

       Drive d1:       Device /dev/da2e
                       Created on vinum.lemis.com at Tue Mar 23 12:30:31 1999
                       Config last updated Tue Mar 23 14:30:32 1999
                       Size:      60105216000 bytes (57320 MB)
                       Used:       2147619328 bytes (2048 MB)
                       Available: 57957596672 bytes (55272 MB)
                       State: up
                       Last error: none
       Drive d2:       Device /dev/da3e
                       Created on vinum.lemis.com at Tue Mar 23 12:30:32 1999
                       Config last updated Tue Mar 23 14:30:33 1999
                       Size:      60105216000 bytes (57320 MB)
                       Used:       2147619328 bytes (2048 MB)
                       Available: 57957596672 bytes (55272 MB)
                       State: up
                       Last error: none

       Volume mirror:  Size: 2147483648 bytes (2048 MB)
                       State: up
                       Flags:
                       2 plexes
                       Read policy: round robin

       Plex mirror.p0: Size:   2147483648 bytes (2048 MB)
                       Subdisks:        1
                       State: up
                       Organization: concat
                       Part of volume mirror
       Plex mirror.p1: Size:   2147483648 bytes (2048 MB)
                       Subdisks:        1
                       State: up
                       Organization: concat
                       Part of volume mirror

       Subdisk mirror.p0.s0:
                       Size:       2147483648 bytes (2048 MB)
                       State: up
                       Plex mirror.p0 at offset 0

       Subdisk mirror.p1.s0:
                       Size:       2147483648 bytes (2048 MB)
                       State: up
                       Plex mirror.p1 at offset 0

     The -v option tells vinum to list the file as it configures.  Subse-
     quently it lists the current configuration in the same format as the list
     -v command.

   Creating more volumes
     Once you have created the vinum volumes, vinum keeps track of them in its
     internal configuration files.  You do not need to create them again.  In
     particular, if you run the create command again, you will create addi-
     tional objects:

     # vinum create sampleconfig
     Configuration summary

     Drives:         2 (4 configured)
     Volumes:        1 (4 configured)
     Plexes:         4 (8 configured)
     Subdisks:       4 (16 configured)

     D d1                    State: up       Device /dev/da2e        Avail: 53224/57320 MB (92%)
     D d2                    State: up       Device /dev/da3e        Avail: 53224/57320 MB (92%)

     V mirror                State: up       Plexes:       4 Size:       2048 MB

     P mirror.p0           C State: up       Subdisks:     1 Size:       2048 MB
     P mirror.p1           C State: up       Subdisks:     1 Size:       2048 MB
     P mirror.p2           C State: up       Subdisks:     1 Size:       2048 MB
     P mirror.p3           C State: up       Subdisks:     1 Size:       2048 MB

     S mirror.p0.s0          State: up       PO:        0  B Size:       2048 MB
     S mirror.p1.s0          State: up       PO:        0  B Size:       2048 MB
     S mirror.p2.s0          State: up       PO:        0  B Size:       2048 MB
     S mirror.p3.s0          State: up       PO:        0  B Size:       2048 MB

     As this example (this time with the -f option) shows, re-running the
     create has created four new plexes, each with a new subdisk.  If you want
     to add other volumes, create new configuration files for them.  They do
     not need to reference the drives that vinum already knows about.  For
     example, to create a volume raid on the four drives /dev/da1e, /dev/da2e,
     /dev/da3e and /dev/da4e, you only need to mention the other two:

           drive d3 device /dev/da1e
           drive d4 device /dev/da4e
           volume raid
             plex org raid5 512k
               sd size 2g drive d1
               sd size 2g drive d2
               sd size 2g drive d3
               sd size 2g drive d4

     With this configuration file, we get:

     # vinum create newconfig
     Configuration summary

     Drives:         4 (4 configured)
     Volumes:        2 (4 configured)
     Plexes:         5 (8 configured)
     Subdisks:       8 (16 configured)

     D d1                    State: up       Device /dev/da2e        Avail: 51176/57320 MB (89%)
     D d2                    State: up       Device /dev/da3e        Avail: 53220/57320 MB (89%)
     D d3                    State: up       Device /dev/da1e        Avail: 53224/57320 MB (92%)
     D d4                    State: up       Device /dev/da4e        Avail: 53224/57320 MB (92%)

     V mirror                State: down     Plexes:       4 Size:       2048 MB
     V raid                  State: down     Plexes:       1 Size:       6144 MB

     P mirror.p0           C State: init     Subdisks:     1 Size:       2048 MB
     P mirror.p1           C State: init     Subdisks:     1 Size:       2048 MB
     P mirror.p2           C State: init     Subdisks:     1 Size:       2048 MB
     P mirror.p3           C State: init     Subdisks:     1 Size:       2048 MB
     P raid.p0            R5 State: init     Subdisks:     4 Size:       6144 MB

     S mirror.p0.s0          State: up       PO:        0  B Size:       2048 MB
     S mirror.p1.s0          State: up       PO:        0  B Size:       2048 MB
     S mirror.p2.s0          State: up       PO:        0  B Size:       2048 MB
     S mirror.p3.s0          State: up       PO:        0  B Size:       2048 MB
     S raid.p0.s0            State: empty    PO:        0  B Size:       2048 MB
     S raid.p0.s1            State: empty    PO:      512 kB Size:       2048 MB
     S raid.p0.s2            State: empty    PO:     1024 kB Size:       2048 MB
     S raid.p0.s3            State: empty    PO:     1536 kB Size:       2048 MB

     Note the size of the RAID-5 plex: it is only 6 GB, although together its
     components use 8 GB of disk space.  This is because the equivalent of one
     subdisk is used for storing parity data.

   Restarting Vinum
     On rebooting the system, start vinum with the start command:

           # vinum start

     This will start all the vinum drives in the system.  If for some reason
     you wish to start only some of them, use the read command.

   Performance considerations
     A number of misconceptions exist about how to set up a RAID array for
     best performance.  In particular, most systems use far too small a stripe
     size.  The following discussion applies to all RAID systems, not just to
     vinum.

     The FreeBSD block I/O system issues requests of between .5kB and 128 kB;
     a typical mix is somewhere round 8 kB.  You can't stop any striping sys-
     tem from breaking a request into two physical requests, and if you make
     the stripe small enough, it can be broken into several.  This will result
     in a significant drop in performance: the decrease in transfer time per
     disk is offset by the order of magnitude greater increase in latency.

     With modern disk sizes and the FreeBSD I/O system, you can expect to have
     a reasonably small number of fragmented requests with a stripe size
     between 256 kB and 512 kB; with correct RAID implementations there is no
     obvious reason not to increase the size to 2 or 4 MB on a large disk.

     When choosing a stripe size, consider that most current UFS file systems
     have cylinder groups 32 MB in size.  If you have a stripe size and number
     of disks both of which are a power of two, it is probable that all
     superblocks and inodes will be placed on the same subdisk, which will
     impact performance significantly.  Choose an odd number instead, for
     example 479 kB.

     The easiest way to consider the impact of any transfer in a multi-access
     system is to look at it from the point of view of the potential bottle-
     neck, the disk subsystem: how much total disk time does the transfer use?
     Since just about everything is cached, the time relationship between the
     request and its completion is not so important: the important parameter
     is the total time that the request keeps the disks active, the time when
     the disks are not available to perform other transfers.  As a result, it
     doesn't really matter if the transfers are happening at the same time or
     different times.  In practical terms, the time we're looking at is the
     sum of the total latency (positioning time and rotational latency, or the
     time it takes for the data to arrive under the disk heads) and the total
     transfer time.  For a given transfer to disks of the same speed, the
     transfer time depends only on the total size of the transfer.

     Consider a typical news article or web page of 24 kB, which will probably
     be read in a single I/O.  Take disks with a transfer rate of 6 MB/s and
     an average positioning time of 8 ms, and a file system with 4 kB blocks.
     Since it's 24 kB, we don't have to worry about fragments, so the file
     will start on a 4 kB boundary.  The number of transfers required depends
     on where the block starts: it's (S + F - 1) / S, where S is the stripe
     size in file system blocks, and F is the file size in file system blocks.

     1.   Stripe size of 4 kB.  You'll have 6 transfers.  Total subsystem
          load: 48 ms latency, 2 ms transfer, 50 ms total.

     2.   Stripe size of 8 kB.  On average, you'll have 3.5 transfers.  Total
          subsystem load: 28 ms latency, 2 ms transfer, 30 ms total.

     3.   Stripe size of 16 kB.  On average, you'll have 2.25 transfers.
          Total subsystem load: 18 ms latency, 2 ms transfer, 20 ms total.

     4.   Stripe size of 256 kB.  On average, you'll have 1.08 transfers.
          Total subsystem load: 8.6 ms latency, 2 ms transfer, 10.6 ms total.

     5.   Stripe size of 4 MB.  On average, you'll have 1.0009 transfers.
          Total subsystem load: 8.01 ms latency, 2 ms transfer, 10.01 ms
          total.

     It appears that some hardware RAID systems have problems with large
     stripes: they appear to always transfer a complete stripe to or from
     disk, so that a large stripe size will have an adverse effect on perfor-
     mance.  vinum does not suffer from this problem: it optimizes all disk
     transfers and does not transfer unneeded data.

     Note that no well-known benchmark program tests true multi-access condi-
     tions (more than 100 concurrent users), so it is difficult to demonstrate
     the validity of these statements.

     Given these considerations, the following factors affect the performance
     of a vinum volume:

     +o   Striping improves performance for multiple access only, since it
         increases the chance of individual requests being on different
         drives.

     +o   Concatenating UFS file systems across multiple drives can also
         improve performance for multiple file access, since UFS divides a
         file system into cylinder groups and attempts to keep files in a sin-
         gle cylinder group.  In general, it is not as effective as striping.

     +o   Mirroring can improve multi-access performance for reads, since by
         default vinum issues consecutive reads to consecutive plexes.

     +o   Mirroring decreases performance for all writes, whether multi-access
         or single access, since the data must be written to both plexes.
         This explains the subdisk layout in the example of a mirroring con-
         figuration above: if the corresponding subdisk in each plex is on a
         different physical disk, the write commands can be issued in paral-
         lel, whereas if they are on the same physical disk, they will be per-
         formed sequentially.

     +o   RAID-5 reads have essentially the same considerations as striped
         reads, unless the striped plex is part of a mirrored volume, in which
         case the performance of the mirrored volume will be better.

     +o   RAID-5 writes are approximately 25% of the speed of striped writes:
         to perform the write, vinum must first read the data block and the
         corresponding parity block, perform some calculations and write back
         the parity block and the data block, four times as many transfers as
         for writing a striped plex.  On the other hand, this is offset by the
         cost of mirroring, so writes to a volume with a single RAID-5 plex
         are approximately half the speed of writes to a correctly configured
         volume with two striped plexes.

     +o   When the vinum configuration changes (for example, adding or removing
         objects, or the change of state of one of the objects), vinum writes
         up to 128 kB of updated configuration to each drive.  The larger the
         number of drives, the longer this takes.

   Creating file systems on Vinum volumes
     You do not need to run disklabel(8) before creating a file system on a
     vinum volume.  Just run newfs(8).  Use the -v option to state that the
     device is not divided into partitions.  For example, to create a file
     system on volume mirror, enter the following command:

           # newfs -v /dev/vinum/mirror

     A number of other considerations apply to vinum configuration:

     +o   There is no advantage in creating multiple drives on a single disk.
         Each drive uses 131.5 kB of data for label and configuration informa-
         tion, and performance will suffer when the configuration changes.
         Use appropriately sized subdisks instead.

     +o   It is possible to increase the size of a concatenated vinum plex, but
         currently the size of striped and RAID-5 plexes cannot be increased.
         Currently the size of an existing UFS file system also cannot be
         increased, but it is planned to make both plexes and file systems
         extensible.

STATE MANAGEMENT
     Vinum objects have the concept of state.  See vinum(4) for more details.
     They are only completely accessible if their state is up.  To change an
     object state to up, use the start command.  To change an object state to
     down, use the stop command.  Normally other states are created automati-
     cally by the relationship between objects.  For example, if you add a
     plex to a volume, the subdisks of the plex will be set in the empty
     state, indicating that, though the hardware is accessible, the data on
     the subdisk is invalid.  As a result of this state, the plex will be set
     in the faulty state.

   The `reviving' state
     In many cases, when you start a subdisk the system must copy data to the
     subdisk.  Depending on the size of the subdisk, this can take a long
     time.  During this time, the subdisk is set in the reviving state.  On
     successful completion of the copy operation, it is automatically set to
     the up state.  It is possible for the process performing the revive to be
     stopped and restarted.  The system keeps track of how far the subdisk has
     been revived, and when the start command is reissued, the copying contin-
     ues from this point.

     In order to maintain the consistency of a volume while one or more of its
     plexes is being revived, vinum writes to subdisks which have been revived
     up to the point of the write.  It may also read from the plex if the area
     being read has already been revived.

GOTCHAS
     The following points are not bugs, and they have good reasons for exist-
     ing, but they have shown to cause confusion.  Each is discussed in the
     appropriate section above.

     1.   vinum drives are UNIX disk partitions and must have the partition
          type vinum.  This is different from ccd(4), which expects partitions
          of type 4.2BSD.  This behaviour of ccd is an invitation to shoot
          yourself in the foot: with ccd you can easily overwrite a file sys-
          tem.  vinum will not permit this.

          For similar reasons, the vinum start command will not accept a drive
          on partition ``c''.  Partition ``c'' is used by the system to repre-
          sent the whole disk, and must be of type unused.  Clearly there is a
          conflict here, which vinum resolves by not using the ``c'' parti-
          tion.

     2.   When you create a volume with multiple plexes, vinum does not auto-
          matically initialize the plexes.  This means that the contents are
          not known, but they are certainly not consistent.  As a result, by
          default vinum sets the state of all newly-created plexes except the
          first to faulty.  In order to synchronize them with the first plex,
          you must start them, which causes vinum to copy the data from a plex
          which is in the up state.  Depending on the size of the subdisks
          involved, this can take a long time.

          In practice, people aren't too interested in what was in the plex
          when it was created, and other volume managers cheat by setting them
          up anyway.  vinum provides two ways to ensure that newly created
          plexes are up:

          +o   Create the plexes and then synchronize them with vinum start.

          +o   Create the volume (not the plex) with the keyword setupstate,
              which tells vinum to ignore any possible inconsistency and set
              the plexes to be up.

     3.   Some of the commands currently supported by vinum are not really
          needed.  For reasons which I don't understand, however, I find that
          users frequently try the label and resetconfig commands, though
          especially resetconfig outputs all sort of dire warnings.  Don't use
          these commands unless you have a good reason to do so.

     4.   Some state transitions are not very intuitive.  In fact, it's not
          clear whether this is a bug or a feature.  If you find that you
          can't start an object in some strange state, such as a reborn sub-
          disk, try first to get it into stopped state, with the stop or stop
          -f commands.  If that works, you should then be able to start it.
          If you find that this is the only way to get out of a position where
          easier methods fail, please report the situation.

     5.   If you build the kernel module with the -DVINUMDEBUG option, you
          must also build vinum with the -DVINUMDEBUG option, since the size
          of some data objects used by both components depends on this option.
          If you don't do so, commands will fail with the message Invalid
          argument, and a console message will be logged such as

          vinumioctl: invalid ioctl from process 247 (vinum): c0e44642

          This error may also occur if you use old versions of KLD or userland
          program.

     6.   The vinum read command has a particularly emetic syntax.  Once it
          was the only way to start vinum, but now the preferred method is
          with vinum start.  vinum read should be used for maintenance pur-
          poses only.  Note that its syntax has changed, and the arguments
          must be disk slices, such as /dev/da0, not partitions such as
          /dev/da0e.

FILES
     /dev/vinum          directory with device nodes for vinum objects
     /dev/vinum/control  control device for vinum
     /dev/vinum/plex     directory containing device nodes for vinum plexes
     /dev/vinum/sd       directory containing device nodes for vinum subdisks

ENVIRONMENT
     VINUM_HISTORY     The name of the log file, by default
                       /var/log/vinum_history.

     VINUM_DATEFORMAT  The format of dates in the log file, by default "%e %b
                       %Y %H:%M:%S".

     EDITOR            The name of the editor to use for editing configuration
                       files, by default vi.

SEE ALSO
     strftime(3), vinum(4), disklabel(8), newfs(8)

     http://www.vinumvm.org/vinum/,
     http://www.vinumvm.org/vinum/how-to-debug.html.

AUTHORS
     Greg Lehey <grog@lemis.com>

HISTORY
     The vinum command first appeared in FreeBSD 3.0.  The RAID-5 component of
     vinum was developed for Cybernet Inc. (www.cybernet.com) for its NetMAX
     product.

FreeBSD 4.10                   December 20, 2000                  FreeBSD 4.10

NAME | SYNOPSIS | COMMANDS | DESCRIPTION | OPTIONS | COMMANDS IN DETAIL | SIMPLIFIED CONFIGURATION | CONFIGURATION FILE | EXAMPLE CONFIGURATION FILE | DRIVE LAYOUT CONSIDERATIONS | LOG FILE | HOW TO SET UP VINUM | STATE MANAGEMENT | GOTCHAS | FILES | ENVIRONMENT | SEE ALSO | AUTHORS | HISTORY

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