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