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NAME    [Toc]    [Back]

     ccdconfig -- configuration utility for the concatenated disk driver

SYNOPSIS    [Toc]    [Back]

     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 [...]]

DESCRIPTION    [Toc]    [Back]

     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

     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)).

EXAMPLES    [Toc]    [Back]

     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(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.  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 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    [Toc]    [Back]

     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(4) controller, or software
 RAID systems such as vinum(8).

FILES    [Toc]    [Back]

     /etc/ccd.conf  default ccd configuration file

SEE ALSO    [Toc]    [Back]

     dd(1), ccd(4), dpt(4), disklabel(8), rc(8), vinum(8)

BUGS    [Toc]    [Back]

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

HISTORY    [Toc]    [Back]

     The ccdconfig utility first appeared in NetBSD 1.0A.

FreeBSD 5.2.1			 July 17, 1995			 FreeBSD 5.2.1
[ Back ]
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