.\" $NetBSD: ccdconfig.8,v 1.1.2.1 1995/11/11 02:43:33 thorpej Exp $ .\" .\" Copyright (c) 1995 Jason R. Thorpe. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 4. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, .\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED .\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, .\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $FreeBSD$ .\" .Dd October 3, 2016 .Dt CCDCONFIG 8 .Os .Sh NAME .Nm ccdconfig .Nd configuration utility for the concatenated disk driver .Sh SYNOPSIS .Nm .Op Fl cv .Ar ccd .Ar ileave .Op Ar flags .Ar dev ... .Nm .Fl C .Op Fl v .Op Fl f Ar config_file .Nm .Fl u .Op Fl v .Ar ccd ... .Nm .Fl U .Op Fl v .Op Fl f Ar config_file .Nm .Fl g .Op Ar ccd ... .Sh DESCRIPTION The .Nm utility is used to dynamically configure and unconfigure concatenated disk devices, or ccds. For more information about the ccd, see .Xr ccd 4 . .Pp The options are as follows: .Bl -tag -width indent .It Fl c Configure a ccd. This is the default behavior of .Nm . .It Fl C Configure all ccd devices listed in the ccd configuration file. .It Fl f Ar config_file When configuring or unconfiguring all devices, read the file .Pa config_file instead of the default .Pa /etc/ccd.conf . .It Fl 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. .It Fl u Unconfigure a ccd. .It Fl U Unconfigure all ccd devices listed the ccd configuration file. .It Fl v Cause .Nm to be verbose. .El .Pp 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 .Dq none . The flags are as follows: .Bd -literal -offset indent 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 .Ed .Pp 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 .Pa flags argument is optional. .Bd -literal -offset indent # # /etc/ccd.conf # Configuration file for concatenated disk devices # # ccd ileave flags component devices ccd0 16 none /dev/da2s1 /dev/da3s1 .Ed .Pp The component devices need to name partitions of type .Li FS_BSDFFS (or .Dq 4.2BSD as shown by .Xr disklabel 8 ) . .Pp If you want to use the .Tn Linux .Xr md 4 compatibility mode, please be sure to read the notes in .Xr ccd 4 . .Sh FILES .Bl -tag -width /etc/ccd.conf -compact .It Pa /etc/ccd.conf default ccd configuration file .El .Sh EXAMPLES A number of .Nm examples are shown below. The arguments passed to .Nm are exactly the same as you might place in the .Pa /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 second slice of /dev/da8 is mirrored with the third slice of /dev/da9 and assigned to ccd0. .Bd -literal # 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 .Ed .Pp The following are matching commands in .Tn Linux and .Fx to create a RAID-0 in .Tn Linux and read it from .Fx . .Bd -literal # 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 .Ed .Pp When you create a new ccd disk you generally want to .Xr fdisk 8 and .Xr 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 .Xr 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. .Bd -literal # disklabel ccd0 > /tmp/disklabel.ccd0 # disklabel -Rr ccd0 /tmp/disklabel.ccd0 # disklabel -e ccd0 .Ed .Pp 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. .Sh 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 .Xr geom 8 and .Xr gvinum 8 . .Sh SEE ALSO .Xr dd 1 , .Xr ccd 4 , .Xr disklabel 8 , .Xr fdisk 8 , .Xr gvinum 8 , .Xr rc 8 .Sh HISTORY The .Nm utility first appeared in .Nx 1.1 . .Sh BUGS The initial disklabel returned by .Xr ccd 4 specifies only 3 partitions. One needs to change the number of partitions to 8 using .Dq Nm disklabel Fl e to get the usual .Bx expectations.