1 .\" $NetBSD: ccdconfig.8,v 1.1.2.1 1995/11/11 02:43:33 thorpej Exp $
3 .\" Copyright (c) 1995 Jason R. Thorpe.
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16 .\" This product includes software developed for the NetBSD Project
17 .\" by Jason R. Thorpe.
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33 .\" $FreeBSD: src/sbin/ccdconfig/ccdconfig.8,v 1.9.2.10 2003/01/26 03:38:39 keramida Exp $
40 .Nd configuration utility for the concatenated disk driver
52 .Op Fl f Ar config_file
61 .Op Fl f Ar config_file
70 utility is used to dynamically configure and unconfigure concatenated disk
71 devices, or ccds. For more information about the ccd, see
74 The options are as follows:
75 .Bl -tag -width indent
77 Configure a ccd. This is the default behavior of
80 Configure all ccd devices listed in the ccd configuration file.
81 .It Fl f Ar config_file
82 When configuring or unconfiguring all devices, read the file
84 instead of the default
87 Dump the current ccd configuration in a format suitable for use as the
88 ccd configuration file. If no arguments are specified, every configured
89 ccd is dumped. Otherwise, the configuration of each listed ccd is dumped.
91 Extract values associated with the name list from
93 instead of the default
98 as the kernel instead of the running kernel (as determined from
103 Unconfigure all ccd devices listed the ccd configuration file.
110 A ccd is described on the command line and in the ccd configuration
111 file by the name of the ccd, the interleave factor, the ccd configuration
112 flags, and a list of one or more devices. The flags may be represented
113 as a decimal number, a hexadecimal number, a comma-separated list
114 of strings, or the word
116 The flags are as follows:
117 .Bd -unfilled -offset indent
118 CCDF_SWAP 0x01 Interleave should be dmmax
119 CCDF_UNIFORM 0x02 Use uniform interleave
120 CCDF_MIRROR 0x04 Support mirroring
121 CCDF_PARITY 0x08 Support parity (not implemented yet)
125 configuration file appears exactly as if it were entered on the command line.
126 Note that on the command line and in the configuration file, the
128 argument is optional.
129 .Bd -unfilled -offset indent
132 # Configuration file for concatenated disk devices
135 # ccd ileave flags component devices
136 ccd0 16 none /dev/da2e /dev/da3e
139 The component devices need to name partitions of type
148 examples are shown below. The arguments passed
151 are exactly the same as you might place in the
153 configuration file. The first example creates a 4-disk stripe out of
154 four scsi disk partitions. The stripe uses a 64 sector interleave.
155 The second example is an example of a complex stripe/mirror combination.
156 It reads as a two disk stripe of da2e and da3e which is mirrored
157 to a two disk stripe of da4e and da5e. The last example is a simple
158 mirror. /dev/da2e is mirrored with /dev/da4e and assigned to ccd0.
160 .Bd -unfilled -offset
161 # ccdconfig ccd0 64 none /dev/da2e /dev/da3e /dev/da4e /dev/da5e
162 # ccdconfig ccd0 128 CCDF_MIRROR /dev/da2e /dev/da3e /dev/da4e /dev/da5e
163 # ccdconfig ccd0 128 CCDF_MIRROR /dev/da2e /dev/da4e
166 When you create a new ccd disk you generally want to
168 it before doing anything else. Once you create the initial label you can
169 edit it, adding additional partitions. The label itself takes up the first
170 16 sectors of the ccd disk. If all you are doing is creating file systems
171 with newfs, you do not have to worry about this as newfs will skip the
172 label area. However, if you intend to
174 to or from a ccd partition it is usually a good idea to construct the
175 partition such that it does not overlap the label area. For example, if
176 you have A ccd disk with 10000 sectors you might create a 'd' partition
177 with offset 16 and size 9984.
179 .Bd -unfilled -offset
180 # disklabel -r -w ccd0c auto
184 The disklabeling of a ccd disk is usually a one-time affair. Unlike other
185 devices, ccd currently requires that you specify partition 'c' when
186 running disklabel. If you reboot the machine and reconfigure the ccd disk,
188 had created before will still be there and not require reinitialization.
189 Beware that changing any ccd parameters: interleave, flags, or the
190 device list making up the ccd disk, will usually destroy any prior
191 data on that ccd disk. If this occurs it is usually a good idea to
192 reinitialize the label before [re]constructing your ccd disk.
194 An error on a ccd disk is usually unrecoverable unless you are using the
195 mirroring option. But mirroring has its own perils: It assumes that
196 both copies of the data at any given sector are the same. This holds true
197 until a write error occurs or until you replace either side of the mirror.
198 This is a poor-man's mirroring implementation. It works well enough that if
199 you begin to get disk errors you should be able to backup the ccd disk,
200 replace the broken hardware, and then regenerate the ccd disk. If you need
201 more than this you should look into external hardware RAID SCSI boxes,
202 RAID controllers such as the
204 controller, or software RAID systems such as
207 .Bl -tag -width /etc/ccd.conf -compact
209 default ccd configuration file
221 utility first appeared in