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

NAME
       ccdconfig -- configuration utility for the concatenated disk driver

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

DESCRIPTION
       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 configura-
       tion flags, and a list of one or	more devices.  The flags may be	repre-
       sented as a decimal number, a  hexadecimal  number,  a  comma-separated
       list of strings,	or the word "none".  The flags are as follows:

	     CCDF_UNIFORM    0x02	     Use uniform interleave
	     CCDF_MIRROR     0x04	     Support mirroring
	     CCDF_NO_OFFSET  0x08	     Do	not use	an offset
	     CCDF_LINUX	     0x0A	     Linux md(4) compatibility

       The  format in the configuration	file appears exactly as	if it were en-
       tered 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/da2s1	/dev/da3s1

       If  you	want to	use the	Linux md(4) compatibility mode,	please be sure
       to read the notes in ccd(4).

FILES
       /etc/ccd.conf  default ccd configuration	file

EXAMPLES
       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/mir-
       ror combination.	 It reads as a two disk	stripe of da4 and da5 which is
       mirrored	 to  a	two disk stripe	of da6 and da7.	 The last example is a
       simple mirror.  The second slice	of /dev/da8 is mirrored	with the third
       slice of	/dev/da9 and assigned to ccd0.

       # ccdconfig ccd0	64 none	/dev/da0s1 /dev/da1s1 /dev/da2s1 /dev/da3s1
       # ccdconfig ccd0	128 CCDF_MIRROR	/dev/da4 /dev/da5 /dev/da6 /dev/da7
       # ccdconfig ccd0	128 CCDF_MIRROR	/dev/da8s2 /dev/da9s3

       The following are matching commands in Linux and	FreeBSD	 to  create  a
       RAID-0 in Linux and read	it from	FreeBSD.

       # Create	a RAID-0 on Linux:
       mdadm --create --chunk=32 --level=0 --raid-devices=2 /dev/md0 \
	  /dev/hda1 /dev/hdb1
       # Make the RAID-0 just created available	on FreeBSD:
       ccdconfig -c /dev/ccd0 32 linux /dev/ada0s1 /dev/ada0s2

       When you	create a new ccd disk you generally want to partition it using
       gpart(8)	 it  before doing anything else.  Beware that changing any ccd
       parameters: interleave, flags, or the device list  making  up  the  ccd
       disk,  will  usually  destroy any prior data on that ccd	disk.  If this
       occurs it is usually a good  idea  to  reinitialize  the	 label	before
       [re]constructing	your ccd disk.

RECOVERY
       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 re-
       generate	the ccd	disk.  If you need more	than this you should look into
       external	hardware RAID SCSI boxes, RAID controllers (see	 GENERIC),  or
       software	RAID systems such as graid(8) or zfs(8).

SEE ALSO
       dd(1), ccd(4), gpart(8),	graid(8), rc(8), zfs(8)

HISTORY
       The ccdconfig utility first appeared in NetBSD 1.1.

FreeBSD	14.3		       January 23, 2025			  CCDCONFIG(8)

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