CCDCONFIG(8)						    BSD 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 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_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 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/da2s1 /dev/da3s1

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

     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/mirror 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 2nd slice of /dev/da8 is mirrored with the 3rd 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 fdisk(8) and disklabel(8) 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(1)
     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 ccd0 > /tmp/disklabel.ccd0
     # disklabel -Rr ccd0 /tmp/disklabel.ccd0
     # disklabel -e ccd0

     The disklabeling of a ccd disk is usually a one-time affair.  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 usually destroy any prior data on that ccd disk.	If this occurs it is usually a good idea to reini-
     tialize 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 regenerate 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 geom(8) and gvinum(8).

SEE ALSO

     dd(1), ccd(4), disklabel(8), fdisk(8), gvinum(8), rc(8)

HISTORY

     The ccdconfig utility first appeared in NetBSD 1.0A.

BUGS

     The initial disklabel returned by ccd(4) specifies only 3 partitions.  One needs to change the number of partitions to 8 using ``disklabel
     -e'' to get the usual BSD expectations.

BSD
								  October 1, 2013							       BSD