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

     ccdconfig -- configuration	utility	for the	concatenated disk driver

     ccdconfig [-cv] ccd ileave	[flags]	dev [file ...]
     ccdconfig -C [-v] [-f config_file]
     ccdconfig -u [-v] ccd [file ...]
     ccdconfig -U [-v] [-f config_file]
     ccdconfig -g [ccd [...]]

     The ccdconfig utility is used to dynamically configure and	unconfigure
     concatenated disk devices,	or ccds.  For more information about the ccd,
     see ccd(4).

     The options are as	follows:

     -c	     Configure a ccd.  This is the default behavior of ccdconfig.

     -C	     Configure all ccd devices listed in the ccd configuration file.

     -f	config_file
	     When configuring or unconfiguring all devices, read the file
	     config_file instead of the	default	/etc/ccd.conf.

     -g	     Dump the current ccd configuration	in a format suitable for use
	     as	the ccd	configuration file.  If	no arguments are specified,
	     every configured ccd is dumped.  Otherwise, the configuration of
	     each listed ccd is	dumped.

     -u	     Unconfigure a ccd.

     -U	     Unconfigure all ccd devices listed	the ccd	configuration file.

     -v	     Cause ccdconfig to	be verbose.

     A ccd is described	on the command line and	in the ccd configuration file
     by	the name of the	ccd, the interleave factor, the	ccd configuration
     flags, and	a list of one or more devices.	The flags may be represented
     as	a decimal number, a hexadecimal	number,	a comma-separated list of
     strings, or the word ``none''.  The flags are as follows:

	   CCDF_SWAP	  0x01	    Interleave should be dmmax
	   CCDF_UNIFORM	  0x02	    Use	uniform	interleave
	   CCDF_MIRROR	  0x04	    Support mirroring
	   CCDF_PARITY	  0x08	    Support parity (not	implemented yet)

     The format	in the configuration file appears exactly as if	it were
     entered on	the command line.  Note	that on	the command line and in	the
     configuration file, the flags argument is optional.

	   # /etc/ccd.conf
	   # Configuration file	for concatenated disk devices

	   # ccd	   ileave  flags   component devices
	   ccd0		   16	   none	   /dev/da2e /dev/da3e

     The component devices need	to name	partitions of type FS_BSDFFS (or
     ``4.2BSD''	as shown by disklabel(8)).

     A number of ccdconfig examples are	shown below.  The arguments passed to
     ccdconfig are exactly the same as you might place in the /etc/ccd.conf
     configuration file.  The first example creates a 4-disk stripe out	of
     four scsi disk partitions.	 The stripe uses a 64 sector interleave.  The
     second example is an example of a complex stripe/mirror combination.  It
     reads as a	two disk stripe	of da2e	and da3e which is mirrored to a	two
     disk stripe of da4e and da5e.  The	last example is	a simple mirror.
     /dev/da2e is mirrored with	/dev/da4e and assigned to ccd0.

     # ccdconfig ccd0 64 none /dev/da2e	/dev/da3e /dev/da4e /dev/da5e
     # ccdconfig ccd0 128 CCDF_MIRROR /dev/da2e	/dev/da3e /dev/da4e /dev/da5e
     # ccdconfig ccd0 128 CCDF_MIRROR /dev/da2e	/dev/da4e

     When you create a new ccd disk you	generally want to disklabel it before
     doing anything else.  Once	you create the initial label you can edit it,
     adding additional partitions.  The	label itself takes up the first	16
     sectors of	the ccd	disk.  If all you are doing is creating	file systems
     with newfs, you do	not have to worry about	this as	newfs will skip	the
     label area.  However, if you intend to dd to or from a ccd	partition it
     is	usually	a good idea to construct the partition such that it does not
     overlap the label area.  For example, if you have A ccd disk with 10000
     sectors you might create a	'd' partition with offset 16 and size 9984.

     # disklabel -r -w ccd0c auto
     # disklabel -e ccd0c

     The disklabeling of a ccd disk is usually a one-time affair.  Unlike
     other devices, ccd	currently requires that	you specify partition 'c' when
     running disklabel.	 If you	reboot the machine and reconfigure the ccd
     disk, the disklabel you had created before	will still be there and	not
     require reinitialization.	Beware that changing any ccd parameters:
     interleave, flags,	or the device list making up the ccd disk, will	usu-
     ally destroy any prior data on that ccd disk.  If this occurs it is usu-
     ally a good idea to reinitialize the label	before [re]constructing	your
     ccd disk.

     An	error on a ccd disk is usually unrecoverable unless you	are using the
     mirroring option.	But mirroring has its own perils:  It assumes that
     both copies of the	data at	any given sector are the same.	This holds
     true until	a write	error occurs or	until you replace either side of the
     mirror.  This is a	poor-man's mirroring implementation.  It works well
     enough that if you	begin to get disk errors you should be able to backup
     the ccd disk, replace the broken hardware,	and then regenerate the	ccd
     disk.  If you need	more than this you should look into external hardware
     RAID SCSI boxes, RAID controllers such as the dpt controller, or software
     RAID systems such as vinum.

     /etc/ccd.conf  default ccd	configuration file

     ccd(4), rc(8), vinum(8)

     The ccdconfig utility first appeared in NetBSD 1.0A.

FreeBSD	11.1			 July 17, 1995			  FreeBSD 11.1


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