Manual Pages  — CCDCONFIG

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).

# 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

# 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 -R 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 reinitialize the label before [re]constructing your ccd disk.