258 lines
7.3 KiB
Groff
258 lines
7.3 KiB
Groff
.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jason R. Thorpe.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $NetBSD: ccdconfig.8,v 1.4 1996/02/28 01:01:17 thorpej Exp $
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.\"
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.Dd March 17, 2022
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.Dt CCDCONFIG 8
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.Os
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.Sh NAME
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.Nm ccdconfig
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.Nd configuration utility for the concatenated disk driver
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.Sh SYNOPSIS
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.Nm
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.Op Fl cv
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.Ar ccd
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.Ar ileave
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.Op Ar flags
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.Ar dev ...
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.Nm
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.Fl C
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.Op Fl v
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.Op Fl f Ar config_file
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.Nm
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.Fl u
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.Op Fl v
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.Ar ccd ...
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.Nm
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.Fl U
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.Op Fl v
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.Op Fl f Ar config_file
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.Nm
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.Fl g
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.Op Ar ccd ...
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.Sh DESCRIPTION
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The
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.Nm
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utility is used to dynamically configure and unconfigure concatenated disk
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devices, or ccds.
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For more information about the ccd, see
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.Xr ccd 4 .
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl c
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Configure a ccd.
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This is the default behavior of
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.Nm .
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.It Fl C
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Configure all ccd devices listed in the ccd configuration file.
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.It Fl f Ar config_file
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When configuring or unconfiguring all devices, read the file
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.Pa config_file
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instead of the default
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.Pa /etc/ccd.conf .
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.It Fl g
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Dump the current ccd configuration in a format suitable for use as the
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ccd configuration file.
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If no arguments are specified, every configured
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ccd is dumped.
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Otherwise, the configuration of each listed ccd is dumped.
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.It Fl u
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Unconfigure a ccd.
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.It Fl U
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Unconfigure all ccd devices listed the ccd configuration file.
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.It Fl v
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Cause
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.Nm
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to be verbose.
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.El
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.Pp
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A ccd is described on the command line and in the ccd configuration
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file by the name of the ccd, the interleave factor, the ccd configuration
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flags, and a list of one or more devices.
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The flags may be represented
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as a decimal number, a hexadecimal number, a comma-separated list
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of strings, or the word
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.Dq none .
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The flags are as follows:
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.Bd -literal -offset indent
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CCDF_UNIFORM 0x02 Use uniform interleave
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CCDF_MIRROR 0x04 Support mirroring
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CCDF_NO_OFFSET 0x08 Do not use an offset
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CCDF_LINUX 0x0A Linux md(4) compatibility
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.Ed
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.Pp
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The format in the
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configuration file appears exactly as if it were entered on the command line.
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Note that on the command line and in the configuration file, the
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.Pa flags
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argument is optional.
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.Bd -literal -offset indent
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#
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# /etc/ccd.conf
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# Configuration file for concatenated disk devices
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#
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# ccd ileave flags component devices
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ccd0 16 none /dev/da2s1 /dev/da3s1
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.Ed
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.Pp
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The component devices need to name partitions of type
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.Li FS_BSDFFS
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(or
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.Dq 4.2BSD
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as shown by
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.Xr disklabel 8 ) .
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.Pp
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If you want to use the
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.Tn Linux
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.Xr md 4
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compatibility mode, please be sure
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to read the notes in
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.Xr ccd 4 .
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.Sh FILES
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.Bl -tag -width /etc/ccd.conf -compact
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.It Pa /etc/ccd.conf
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default ccd configuration file
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.El
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.Sh EXAMPLES
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A number of
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.Nm
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examples are shown below.
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The arguments passed
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to
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.Nm
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are exactly the same as you might place in the
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.Pa /etc/ccd.conf
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configuration file.
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The first example creates a 4-disk stripe out of
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four scsi disk partitions.
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The stripe uses a 64 sector interleave.
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The second example is an example of a complex stripe/mirror combination.
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It reads as a two disk stripe of da4 and da5 which is mirrored
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to a two disk stripe of da6 and da7.
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The last example is a simple
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mirror.
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The second slice of /dev/da8 is mirrored with the third slice of /dev/da9
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and assigned to ccd0.
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.Bd -literal
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# ccdconfig ccd0 64 none /dev/da0s1 /dev/da1s1 /dev/da2s1 /dev/da3s1
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# ccdconfig ccd0 128 CCDF_MIRROR /dev/da4 /dev/da5 /dev/da6 /dev/da7
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# ccdconfig ccd0 128 CCDF_MIRROR /dev/da8s2 /dev/da9s3
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.Ed
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.Pp
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The following are matching commands in
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.Tn Linux
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and
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.Fx
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to create a RAID-0 in
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.Tn Linux
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and read it from
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.Fx .
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.Bd -literal
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# Create a RAID-0 on Linux:
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mdadm --create --chunk=32 --level=0 --raid-devices=2 /dev/md0 \\
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/dev/hda1 /dev/hdb1
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# Make the RAID-0 just created available on FreeBSD:
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ccdconfig -c /dev/ccd0 32 linux /dev/ada0s1 /dev/ada0s2
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.Ed
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.Pp
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When you create a new ccd disk you generally want to
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.Xr fdisk 8
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and
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.Xr disklabel 8
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it before doing anything else.
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Once you create the initial label you can
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edit it, adding additional partitions.
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The label itself takes up the first
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16 sectors of the ccd disk.
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If all you are doing is creating file systems
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with newfs, you do not have to worry about this as newfs will skip the
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label area.
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However, if you intend to
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.Xr dd 1
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to or from a ccd partition it is usually a good idea to construct the
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partition such that it does not overlap the label area.
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For example, if
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you have A ccd disk with 10000 sectors you might create a 'd' partition
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with offset 16 and size 9984.
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.Bd -literal
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# disklabel ccd0 > /tmp/disklabel.ccd0
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# disklabel -R ccd0 /tmp/disklabel.ccd0
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# disklabel -e ccd0
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.Ed
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.Pp
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The disklabeling of a ccd disk is usually a one-time affair.
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If you reboot the machine and reconfigure the ccd disk,
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the disklabel you
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had created before will still be there and not require reinitialization.
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Beware that changing any ccd parameters: interleave, flags, or the
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device list making up the ccd disk, will usually destroy any prior
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data on that ccd disk.
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If this occurs it is usually a good idea to
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reinitialize the label before [re]constructing your ccd disk.
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.Sh RECOVERY
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An error on a ccd disk is usually unrecoverable unless you are using the
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mirroring option.
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But mirroring has its own perils: It assumes that
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both copies of the data at any given sector are the same.
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This holds true
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until a write error occurs or until you replace either side of the mirror.
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This is a poor-man's mirroring implementation.
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It works well enough that if
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you begin to get disk errors you should be able to backup the ccd disk,
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replace the broken hardware, and then regenerate the ccd disk.
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If you need
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more than this you should look into external hardware RAID SCSI boxes,
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RAID controllers (see GENERIC),
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or software RAID systems such as
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.Xr geom 8
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and
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.Xr gvinum 8 .
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.Sh SEE ALSO
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.Xr dd 1 ,
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.Xr ccd 4 ,
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.Xr disklabel 8 ,
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.Xr fdisk 8 ,
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.Xr gvinum 8 ,
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.Xr rc 8
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.Sh HISTORY
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The
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.Nm
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utility first appeared in
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.Nx 1.1 .
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.Sh BUGS
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The initial disklabel returned by
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.Xr ccd 4
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specifies only 3 partitions.
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One needs to change the number of partitions to 8 using
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.Dq Nm disklabel Fl e
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to get the usual
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.Bx
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expectations.
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