1.\" $NetBSD: ccdconfig.8,v 1.1.2.1 1995/11/11 02:43:33 thorpej Exp $ 2.\" 3.\" Copyright (c) 1995 Jason R. Thorpe. 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 4. The name of the author may not be used to endorse or promote products 15.\" derived from this software without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 22.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 24.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 25.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd October 3, 2016 32.Dt CCDCONFIG 8 33.Os 34.Sh NAME 35.Nm ccdconfig 36.Nd configuration utility for the concatenated disk driver 37.Sh SYNOPSIS 38.Nm 39.Op Fl cv 40.Ar ccd 41.Ar ileave 42.Op Ar flags 43.Ar dev ... 44.Nm 45.Fl C 46.Op Fl v 47.Op Fl f Ar config_file 48.Nm 49.Fl u 50.Op Fl v 51.Ar ccd ... 52.Nm 53.Fl U 54.Op Fl v 55.Op Fl f Ar config_file 56.Nm 57.Fl g 58.Op Ar ccd ... 59.Sh DESCRIPTION 60The 61.Nm 62utility is used to dynamically configure and unconfigure concatenated disk 63devices, or ccds. 64For more information about the ccd, see 65.Xr ccd 4 . 66.Pp 67The options are as follows: 68.Bl -tag -width indent 69.It Fl c 70Configure a ccd. 71This is the default behavior of 72.Nm . 73.It Fl C 74Configure all ccd devices listed in the ccd configuration file. 75.It Fl f Ar config_file 76When configuring or unconfiguring all devices, read the file 77.Pa config_file 78instead of the default 79.Pa /etc/ccd.conf . 80.It Fl g 81Dump the current ccd configuration in a format suitable for use as the 82ccd configuration file. 83If no arguments are specified, every configured 84ccd is dumped. 85Otherwise, the configuration of each listed ccd is dumped. 86.It Fl u 87Unconfigure a ccd. 88.It Fl U 89Unconfigure all ccd devices listed the ccd configuration file. 90.It Fl v 91Cause 92.Nm 93to be verbose. 94.El 95.Pp 96A ccd is described on the command line and in the ccd configuration 97file by the name of the ccd, the interleave factor, the ccd configuration 98flags, and a list of one or more devices. 99The flags may be represented 100as a decimal number, a hexadecimal number, a comma-separated list 101of strings, or the word 102.Dq none . 103The flags are as follows: 104.Bd -literal -offset indent 105CCDF_UNIFORM 0x02 Use uniform interleave 106CCDF_MIRROR 0x04 Support mirroring 107CCDF_NO_OFFSET 0x08 Do not use an offset 108CCDF_LINUX 0x0A Linux md(4) compatibility 109.Ed 110.Pp 111The format in the 112configuration file appears exactly as if it were entered on the command line. 113Note that on the command line and in the configuration file, the 114.Pa flags 115argument is optional. 116.Bd -literal -offset indent 117# 118# /etc/ccd.conf 119# Configuration file for concatenated disk devices 120# 121 122# ccd ileave flags component devices 123ccd0 16 none /dev/da2s1 /dev/da3s1 124.Ed 125.Pp 126The component devices need to name partitions of type 127.Li FS_BSDFFS 128(or 129.Dq 4.2BSD 130as shown by 131.Xr disklabel 8 ) . 132.Pp 133If you want to use the 134.Tn Linux 135.Xr md 4 136compatibility mode, please be sure 137to read the notes in 138.Xr ccd 4 . 139.Sh FILES 140.Bl -tag -width /etc/ccd.conf -compact 141.It Pa /etc/ccd.conf 142default ccd configuration file 143.El 144.Sh EXAMPLES 145A number of 146.Nm 147examples are shown below. 148The arguments passed 149to 150.Nm 151are exactly the same as you might place in the 152.Pa /etc/ccd.conf 153configuration file. 154The first example creates a 4-disk stripe out of 155four scsi disk partitions. 156The stripe uses a 64 sector interleave. 157The second example is an example of a complex stripe/mirror combination. 158It reads as a two disk stripe of da4 and da5 which is mirrored 159to a two disk stripe of da6 and da7. 160The last example is a simple 161mirror. 162The second slice of /dev/da8 is mirrored with the third slice of /dev/da9 163and assigned to ccd0. 164.Bd -literal 165# ccdconfig ccd0 64 none /dev/da0s1 /dev/da1s1 /dev/da2s1 /dev/da3s1 166# ccdconfig ccd0 128 CCDF_MIRROR /dev/da4 /dev/da5 /dev/da6 /dev/da7 167# ccdconfig ccd0 128 CCDF_MIRROR /dev/da8s2 /dev/da9s3 168.Ed 169.Pp 170The following are matching commands in 171.Tn Linux 172and 173.Fx 174to create a RAID-0 in 175.Tn Linux 176and read it from 177.Fx . 178.Bd -literal 179# Create a RAID-0 on Linux: 180mdadm --create --chunk=32 --level=0 --raid-devices=2 /dev/md0 \\ 181 /dev/hda1 /dev/hdb1 182# Make the RAID-0 just created available on FreeBSD: 183ccdconfig -c /dev/ccd0 32 linux /dev/ada0s1 /dev/ada0s2 184.Ed 185.Pp 186When you create a new ccd disk you generally want to 187.Xr fdisk 8 188and 189.Xr disklabel 8 190it before doing anything else. 191Once you create the initial label you can 192edit it, adding additional partitions. 193The label itself takes up the first 19416 sectors of the ccd disk. 195If all you are doing is creating file systems 196with newfs, you do not have to worry about this as newfs will skip the 197label area. 198However, if you intend to 199.Xr dd 1 200to or from a ccd partition it is usually a good idea to construct the 201partition such that it does not overlap the label area. 202For example, if 203you have A ccd disk with 10000 sectors you might create a 'd' partition 204with offset 16 and size 9984. 205.Bd -literal 206# disklabel ccd0 > /tmp/disklabel.ccd0 207# disklabel -Rr ccd0 /tmp/disklabel.ccd0 208# disklabel -e ccd0 209.Ed 210.Pp 211The disklabeling of a ccd disk is usually a one-time affair. 212If you reboot the machine and reconfigure the ccd disk, 213the disklabel you 214had created before will still be there and not require reinitialization. 215Beware that changing any ccd parameters: interleave, flags, or the 216device list making up the ccd disk, will usually destroy any prior 217data on that ccd disk. 218If this occurs it is usually a good idea to 219reinitialize the label before [re]constructing your ccd disk. 220.Sh RECOVERY 221An error on a ccd disk is usually unrecoverable unless you are using the 222mirroring option. 223But mirroring has its own perils: It assumes that 224both copies of the data at any given sector are the same. 225This holds true 226until a write error occurs or until you replace either side of the mirror. 227This is a poor-man's mirroring implementation. 228It works well enough that if 229you begin to get disk errors you should be able to backup the ccd disk, 230replace the broken hardware, and then regenerate the ccd disk. 231If you need 232more than this you should look into external hardware RAID SCSI boxes, 233RAID controllers (see GENERIC), 234or software RAID systems such as 235.Xr geom 8 236and 237.Xr gvinum 8 . 238.Sh SEE ALSO 239.Xr dd 1 , 240.Xr ccd 4 , 241.Xr disklabel 8 , 242.Xr fdisk 8 , 243.Xr gvinum 8 , 244.Xr rc 8 245.Sh HISTORY 246The 247.Nm 248utility first appeared in 249.Nx 1.1 . 250.Sh BUGS 251The initial disklabel returned by 252.Xr ccd 4 253specifies only 3 partitions. 254One needs to change the number of partitions to 8 using 255.Dq Nm disklabel Fl e 256to get the usual 257.Bx 258expectations. 259