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

NAME
     dump -- filesystem	backup

SYNOPSIS
     dump [-0123456789acknu] [-B records] [-b blocksize] [-d density]
	  [-f file] [-h	level] [-s feet] [-T date] filesystem
     dump [-W |	-w]

     (The 4.3BSD option	syntax is implemented for backward compatibility, but
     is	not documented here.)

DESCRIPTION
     Dump examines files on a filesystem and determines	which files need to be
     backed up.	These files are	copied to the given disk, tape or other	stor-
     age medium	for safe keeping (see the -f option below for doing remote
     backups).	A dump that is larger than the output medium is	broken into
     multiple volumes.	On most	media the size is determined by	writing	until
     an	end-of-media indication	is returned.  This can be enforced by using
     the -a option.

     On	media that cannot reliably return an end-of-media indication (such as
     some cartridge tape drives) each volume is	of a fixed size; the actual
     size is determined	by the tape size and density and/or block count
     options below.  By	default, the same output file name is used for each
     volume after prompting the	operator to change media.

     The following options are supported by dump:

     -0-9    Dump levels.  A level 0, full backup, guarantees the entire file
	     system is copied (but see also the	-h option below).  A level
	     number above 0, incremental backup, tells dump to copy all	files
	     new or modified since the last dump of any	lower level.  The
	     default level is 9.

     -B	records
	     The number	of 1 KB	blocks per volume.  This option	overrides the
	     calculation of tape size based on length and density.

     -a	     ``auto-size''.  Bypass all	tape length considerations, and
	     enforce writing until an end-of-media indication is returned.
	     This fits best for	most modern tape drives.  Use of this option
	     is	particularly recommended when appending	to an existing tape,
	     or	using a	tape drive with	hardware compression (where you	can
	     never be sure about the compression ratio).

     -b	blocksize
	     The number	of kilobytes per dump record.

     -c	     Change the	defaults for use with a	cartridge tape drive, with a
	     density of	8000 bpi, and a	length of 1700 feet.

     -h	level
	     Honor the user ``nodump'' flag only for dumps at or above the
	     given level.  The default honor level is 1, so that incremental
	     backups omit such files but full backups retain them.

     -d	density
	     Set tape density to density.  The default is 1600BPI.

     -f	file
	     Write the backup to file; file may	be a special device file like
	     /dev/rst0 (a tape drive), /dev/rfd1 (a floppy disk	drive),	an
	     ordinary file, or `-' (the	standard output).  Multiple file names
	     may be given as a single argument separated by commas.  Each file
	     will be used for one dump volume in the order listed; if the dump
	     requires more volumes than	the number of names given, the last
	     file name will used for all remaining volumes after prompting for
	     media changes.  If	the name of the	file is	of the form
	     ``host:file'', or ``user@host:file'', dump	writes to the named
	     file on the remote	host using rmt(8).  The	default	path name of
	     the remote	rmt(8) program is /etc/rmt; this can be	overridden by
	     the environment variable RMT.

     -k	     Use Kerberos authentication to talk to remote tape	servers.
	     (Only available if	this option was	enabled	when dump was com-
	     piled.)

     -n	     Whenever dump requires operator attention,	notify all operators
	     in	the group ``operator'' by means	similar	to a wall(1).

     -s	feet
	     Attempt to	calculate the amount of	tape needed at a particular
	     density.  If this amount is exceeded, dump	prompts	for a new
	     tape.  It is recommended to be a bit conservative on this option.
	     The default tape length is	2300 feet.

     -T	date
	     Use the specified date as the starting time for the dump instead
	     of	the time determined from looking in /etc/dumpdates.  The for-
	     mat of date is the	same as	that of	ctime(3).  This	option is use-
	     ful for automated dump scripts that wish to dump over a specific
	     period of time.  The -T option is mutually	exclusive from the -u
	     option.

     -u	     Update the	file /etc/dumpdates after a successful dump.  The for-
	     mat of /etc/dumpdates is readable by people, consisting of	one
	     free format record	per line: filesystem name, increment level and
	     ctime(3) format dump date.	 There may be only one entry per
	     filesystem	at each	level.	The file /etc/dumpdates	may be edited
	     to	change any of the fields, if necessary.

     -W	     Dump tells	the operator what file systems need to be dumped.
	     This information is gleaned from the files	/etc/dumpdates and
	     /etc/fstab.  The -W option	causes dump to print out, for each
	     file system in /etc/dumpdates the most recent dump	date and
	     level, and	highlights those file systems that should be dumped.
	     If	the -W option is set, all other	options	are ignored, and dump
	     exits immediately.

     -w	     Is	like W,	but prints only	those filesystems which	need to	be
	     dumped.

     Dump requires operator intervention on these conditions: end of tape, end
     of	dump, tape write error,	tape open error	or disk	read error (if there
     are more than a threshold of 32).	In addition to alerting	all operators
     implied by	the -n key, dump interacts with	the operator on	dump's control
     terminal at times when dump can no	longer proceed,	or if something	is
     grossly wrong.  All questions dump	poses must be answered by typing
     ``yes'' or	``no'',	appropriately.

     Since making a dump involves a lot	of time	and effort for full dumps,
     dump checkpoints itself at	the start of each tape volume.	If writing
     that volume fails for some	reason,	dump will, with	operator permission,
     restart itself from the checkpoint	after the old tape has been rewound
     and removed, and a	new tape has been mounted.

     Dump tells	the operator what is going on at periodic intervals, including
     usually low estimates of the number of blocks to write, the number	of
     tapes it will take, the time to completion, and the time to the tape
     change.  The output is verbose, so	that others know that the terminal
     controlling dump is busy, and will	be for some time.

     In	the event of a catastrophic disk event,	the time required to restore
     all the necessary backup tapes or files to	disk can be kept to a minimum
     by	staggering the incremental dumps.  An efficient	method of staggering
     incremental dumps to minimize the number of tapes follows:

	   +o   Always start with a level 0 backup, for example:

		     /sbin/dump	-0u -f /dev/nrst0 /usr/src

	       This should be done at set intervals, say once a	month or once
	       every two months, and on	a set of fresh tapes that is saved
	       forever.

	   +o   After a level 0,	dumps of active	file systems are taken on a
	       daily basis, using a modified Tower of Hanoi algorithm, with
	       this sequence of	dump levels:

		     3 2 5 4 7 6 9 8 9 9 ...

	       For the daily dumps, it should be possible to use a fixed num-
	       ber of tapes for	each day, used on a weekly basis.  Each	week,
	       a level 1 dump is taken,	and the	daily Hanoi sequence repeats
	       beginning with 3.  For weekly dumps, another fixed set of tapes
	       per dumped file system is used, also on a cyclical basis.

     After several months or so, the daily and weekly tapes should get rotated
     out of the	dump cycle and fresh tapes brought in.

ENVIRONMENT
     The environment variable RMT will be used to determine the	pathname of
     the remote	rmt(8) program.

FILES
     /dev/rst0	     default tape unit to dump to
     /etc/dumpdates  dump date records
     /etc/fstab	     dump table: file systems and frequency
     /etc/group	     to	find group operator

SEE ALSO
     fstab(5), ft(8), restore(8), rmt(8)

DIAGNOSTICS
     Many, and verbose.

     Dump exits	with zero status on success.  Startup errors are indicated
     with an exit code of 1; abnormal termination is indicated with an exit
     code of 3.

BUGS
     Fewer than	32 read	errors on the filesystem are ignored.

     Each reel requires	a new process, so parent processes for reels already
     written just hang around until the	entire tape is written.

     Currently,	physio(9) slices all requests into chunks of 64	KB.  There-
     fore, it is impossible to use a larger tape blocksize, so dump will pre-
     vent this from happening.

     Dump with the -W or -w options does not report filesystems	that have
     never been	recorded in /etc/dumpdates, even if listed in /etc/fstab.

     It	would be nice if dump knew about the dump sequence, kept track of the
     tapes scribbled on, told the operator which tape to mount when, and pro-
     vided more	assistance for the operator running restore.

     dump cannot do remote backups without being run as	root, due to its secu-
     rity history.  This will be fixed in a later version of FreeBSD.
     Presently,	it work	if you set it setuid (like it used to be), but this
     might constitute a	security risk.

HISTORY
     A dump command appeared in	Version	6 AT&T UNIX.

4th Berkeley Distribution	 June 16, 1993	     4th Berkeley Distribution

NAME | SYNOPSIS | DESCRIPTION | ENVIRONMENT | FILES | SEE ALSO | DIAGNOSTICS | BUGS | HISTORY

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