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519561f7 NB |
1 | .\" Copyright Neil Brown and others. |
2 | .\" This program is free software; you can redistribute it and/or modify | |
3 | .\" it under the terms of the GNU General Public License as published by | |
4 | .\" the Free Software Foundation; either version 2 of the License, or | |
5 | .\" (at your option) any later version. | |
6 | .\" See file COPYING in distribution for details. | |
56eb10c0 NB |
7 | .TH MDADM.CONF 5 |
8 | .SH NAME | |
93e790af | 9 | mdadm.conf \- configuration for management of Software RAID with mdadm |
56eb10c0 NB |
10 | .SH SYNOPSIS |
11 | /etc/mdadm.conf | |
12 | .SH DESCRIPTION | |
13 | .PP | |
51ac42e3 | 14 | .I mdadm |
11a3e71d | 15 | is a tool for creating, managing, and monitoring RAID devices using the |
56eb10c0 NB |
16 | .B md |
17 | driver in Linux. | |
18 | .PP | |
19 | Some common tasks, such as assembling all arrays, can be simplified | |
2d465520 | 20 | by describing the devices and arrays in this configuration file. |
56eb10c0 NB |
21 | |
22 | .SS SYNTAX | |
23 | The file should be seen as a collection of words separated by white | |
24 | space (space, tab, or newline). | |
11a3e71d | 25 | Any word that beings with a hash sign (#) starts a comment and that |
2d465520 | 26 | word together with the remainder of the line is ignored. |
56eb10c0 | 27 | |
2d465520 | 28 | Any line that starts with white space (space or tab) is treated as |
56eb10c0 NB |
29 | though it were a continuation of the previous line. |
30 | ||
31 | Empty lines are ignored, but otherwise each (non continuation) line | |
2d465520 | 32 | must start with a keyword as listed below. The keywords are case |
e0d19036 | 33 | insensitive and can be abbreviated to 3 characters. |
56eb10c0 NB |
34 | |
35 | The keywords are: | |
36 | .TP | |
37 | .B DEVICE | |
38 | A | |
39 | .B device | |
40 | line lists the devices (whole devices or partitions) that might contain | |
41 | a component of an MD array. When looking for the components of an | |
42 | array, | |
51ac42e3 | 43 | .I mdadm |
2d465520 | 44 | will scan these devices (or any devices listed on the command line). |
56eb10c0 NB |
45 | |
46 | The | |
47 | .B device | |
48 | line may contain a number of different devices (separated by spaces) | |
49 | and each device name can contain wild cards as defined by | |
50 | .BR glob (7). | |
51 | ||
52 | Also, there may be several device lines present in the file. | |
53 | ||
5787fa49 NB |
54 | Alternatively, a |
55 | .B device | |
8fd8d9c4 N |
56 | line can contain either of both of the words |
57 | .B containers | |
58 | and | |
5787fa49 | 59 | .BR partitions . |
8fd8d9c4 N |
60 | The word |
61 | .B containers | |
62 | will cause | |
63 | .I mdadm | |
64 | to look for assembled CONTAINER arrays and included them as a source | |
65 | for assembling further arrays. | |
66 | .PP | |
67 | The word | |
68 | .I partitions | |
69 | will cause | |
5787fa49 NB |
70 | .I mdadm |
71 | to read | |
72 | .I /proc/partitions | |
35cc5be4 | 73 | and include all devices and partitions found therein. |
5787fa49 NB |
74 | .I mdadm |
75 | does not use the names from | |
76 | .I /proc/partitions | |
77 | but only the major and minor device numbers. It scans | |
78 | .I /dev | |
79 | to find the name that matches the numbers. | |
80 | ||
8fd8d9c4 | 81 | If no DEVICE line is present, then "DEVICE partitions containers" is assumed. |
a99d6b66 | 82 | |
11a3e71d NB |
83 | For example: |
84 | .IP | |
85 | DEVICE /dev/hda* /dev/hdc* | |
86 | .br | |
87 | DEV /dev/sd* | |
88 | .br | |
89 | DEVICE /dev/discs/disc*/disc | |
5787fa49 NB |
90 | .br |
91 | DEVICE partitions | |
11a3e71d | 92 | |
56eb10c0 NB |
93 | .TP |
94 | .B ARRAY | |
11a3e71d | 95 | The ARRAY lines identify actual arrays. The second word on the line |
8fd8d9c4 | 96 | may be the name of the device where the array is normally |
11a3e71d NB |
97 | assembled, such as |
98 | .BR /dev/md1 . | |
8fd8d9c4 N |
99 | If no device name is given, |
100 | .I mdadm | |
101 | will use various heuristic to determine an appropriate name. | |
102 | .PP | |
e0d19036 NB |
103 | Subsequent words identify the array, or identify the array as a member |
104 | of a group. If multiple identities are given, | |
2d465520 NB |
105 | then a component device must match ALL identities to be considered a |
106 | match. Each identity word has a tag, and equals sign, and some value. | |
107 | The tags are: | |
11a3e71d NB |
108 | |
109 | .RS 4 | |
110 | .TP | |
111 | .B uuid= | |
112 | The value should be a 128 bit uuid in hexadecimal, with punctuation | |
113 | interspersed if desired. This must match the uuid stored in the | |
114 | superblock. | |
115 | .TP | |
947fd4dd NB |
116 | .B name= |
117 | The value should be a simple textual name as was given to | |
118 | .I mdadm | |
119 | when the array was created. This must match the name stored in the | |
120 | superblock on a device for that device to be included in the array. | |
35cc5be4 | 121 | Not all superblock formats support names. |
947fd4dd | 122 | .TP |
7e23fc43 | 123 | .B super\-minor= |
11a3e71d NB |
124 | The value is an integer which indicates the minor number that was |
125 | stored in the superblock when the array was created. When an array is | |
126 | created as /dev/mdX, then the minor number X is stored. | |
127 | .TP | |
128 | .B devices= | |
56eedc1a NB |
129 | The value is a comma separated list of device names or device name |
130 | patterns. | |
131 | Only devices with names which match one entry in the list will be used | |
132 | to assemble the array. Note that the devices | |
11a3e71d NB |
133 | listed there must also be listed on a DEVICE line. |
134 | .TP | |
135 | .B level= | |
136 | The value is a raid level. This is not normally used to | |
137 | identify an array, but is supported so that the output of | |
138 | ||
7e23fc43 | 139 | .B "mdadm \-\-examine \-\-scan" |
11a3e71d NB |
140 | |
141 | can be use directly in the configuration file. | |
142 | .TP | |
7e23fc43 | 143 | .B num\-devices= |
b83d95f3 | 144 | The value is the number of devices in a complete active array. As with |
11a3e71d NB |
145 | .B level= |
146 | this is mainly for compatibility with the output of | |
56eb10c0 | 147 | |
7e23fc43 | 148 | .BR "mdadm \-\-examine \-\-scan" . |
e0d19036 | 149 | |
058574b1 NB |
150 | .TP |
151 | .B spares= | |
152 | The value is a number of spare devices to expect the array to have. | |
7e23fc43 | 153 | .B mdadm \-\-monitor |
058574b1 NB |
154 | will report an array if it is found to have fewer than this number of |
155 | spares when | |
7e23fc43 | 156 | .B \-\-monitor |
058574b1 | 157 | starts or when |
7e23fc43 | 158 | .B \-\-oneshot |
058574b1 NB |
159 | is used. |
160 | ||
e0d19036 | 161 | .TP |
7e23fc43 | 162 | .B spare\-group= |
e0d19036 NB |
163 | The value is a textual name for a group of arrays. All arrays with |
164 | the same | |
7e23fc43 | 165 | .B spare\-group |
e0d19036 NB |
166 | name are considered to be part of the same group. The significance of |
167 | a group of arrays is that | |
51ac42e3 | 168 | .I mdadm |
e0d19036 NB |
169 | will, when monitoring the arrays, move a spare drive from one array in |
170 | a group to another array in that group if the first array had a failed | |
171 | or missing drive but no spare. | |
dd0781e5 NB |
172 | |
173 | .TP | |
174 | .B auto= | |
175 | This option declares to | |
51ac42e3 | 176 | .I mdadm |
dd0781e5 NB |
177 | that it should try to create the device file of the array if it |
178 | doesn't already exist, or exists but with the wrong device number. | |
179 | ||
180 | The value of this option can be "yes" or "md" to indicate that a | |
181 | traditional, non-partitionable md array should be created, or "mdp", | |
182 | "part" or "partition" to indicate that a partitionable md array (only | |
183 | available in linux 2.6 and later) should be used. This later set can | |
184 | also have a number appended to indicate how many partitions to create | |
185 | device files for, e.g. | |
186 | .BR auto=mdp5 . | |
187 | The default is 4. | |
7ef02d01 NB |
188 | |
189 | .TP | |
190 | .B bitmap= | |
191 | The option specifies a file in which a write-intent bitmap should be | |
192 | found. When assembling the array, | |
193 | .I mdadm | |
194 | will provide this file to the | |
195 | .B md | |
196 | driver as the bitmap file. This has the same function as the | |
7e23fc43 | 197 | .B \-\-bitmap\-file |
7ef02d01 | 198 | option to |
7e23fc43 | 199 | .BR \-\-assemble . |
058574b1 NB |
200 | |
201 | .TP | |
202 | .B metadata= | |
203 | Specify the metadata format that the array has. This is mainly | |
204 | recognised for comparability with the output of | |
7e23fc43 | 205 | .BR "mdadm \-Es" . |
058574b1 | 206 | |
8fd8d9c4 N |
207 | .TP |
208 | .B container= | |
209 | Specify that this array is a member array of some container. The | |
210 | value given can be either a path name in /dev, or a UUID of the | |
211 | container array. | |
212 | ||
213 | .IP | |
214 | .B member= | |
215 | Specify that this array is a member array of some container. Each | |
216 | type of container has some way to enumerate member arrays, often a | |
217 | simple sequence number. The value identifies which member of a | |
218 | container the array is. It will usually accompany a 'container=' word. | |
11a3e71d | 219 | .RE |
e0d19036 NB |
220 | |
221 | .TP | |
222 | .B MAILADDR | |
223 | The | |
224 | .B mailaddr | |
225 | line gives an E-mail address that alerts should be | |
226 | sent to when | |
51ac42e3 | 227 | .I mdadm |
e0d19036 | 228 | is running in |
7e23fc43 | 229 | .B \-\-monitor |
e0d19036 | 230 | mode (and was given the |
7e23fc43 | 231 | .B \-\-scan |
e0d19036 NB |
232 | option). There should only be one |
233 | .B MAILADDR | |
234 | line and it should have only one address. | |
235 | ||
236 | ||
4948b8f7 NB |
237 | .TP |
238 | .B MAILFROM | |
239 | The | |
240 | .B mailfrom | |
93e790af | 241 | line (which can only be abbreviated to at least 5 characters) gives an |
4948b8f7 NB |
242 | address to appear in the "From" address for alert mails. This can be |
243 | useful if you want to explicitly set a domain, as the default from | |
244 | address is "root" with no domain. All words on this line are | |
245 | catenated with spaces to form the address. | |
246 | ||
247 | Note that this value cannot be set via the | |
248 | .I mdadm | |
249 | commandline. It is only settable via the config file. | |
250 | ||
e0d19036 NB |
251 | .TP |
252 | .B PROGRAM | |
253 | The | |
254 | .B program | |
255 | line gives the name of a program to be run when | |
7e23fc43 | 256 | .B "mdadm \-\-monitor" |
e0d19036 NB |
257 | detects potentially interesting events on any of the arrays that it |
258 | is monitoring. This program gets run with two or three arguments, they | |
259 | being the Event, the md device, and possibly the related component | |
260 | device. | |
261 | ||
262 | There should only be one | |
263 | .B program | |
264 | line and it should be give only one program. | |
265 | ||
5bbb4842 NB |
266 | |
267 | .TP | |
268 | .B CREATE | |
269 | The | |
270 | .B create | |
058574b1 | 271 | line gives default values to be used when creating arrays and device entries for |
5bbb4842 NB |
272 | arrays. |
273 | These include: | |
274 | ||
275 | .RS 4 | |
276 | .TP | |
277 | .B owner= | |
278 | .TP | |
279 | .B group= | |
280 | These can give user/group ids or names to use instead of system | |
281 | defaults (root/wheel or root/disk). | |
282 | .TP | |
283 | .B mode= | |
284 | An octal file mode such as 0660 can be given to override the default | |
285 | of 0600. | |
286 | .TP | |
287 | .B auto= | |
288 | This corresponds to the | |
7e23fc43 | 289 | .B \-\-auto |
5bbb4842 NB |
290 | flag to mdadm. Give |
291 | .BR yes , | |
292 | .BR md , | |
293 | .BR mdp , | |
294 | .B part | |
b3f1c093 | 295 | \(em possibly followed by a number of partitions \(em to indicate how |
5bbb4842 NB |
296 | missing device entries should be created. |
297 | ||
058574b1 NB |
298 | .TP |
299 | .B metadata= | |
300 | The name of the metadata format to use if none is explicitly given. | |
301 | This can be useful to impose a system-wide default of version-1 superblocks. | |
302 | ||
38098016 NB |
303 | .TP |
304 | .B symlinks=no | |
305 | Normally when creating devices in | |
306 | .B /dev/md/ | |
307 | .I mdadm | |
308 | will create a matching symlink from | |
309 | .B /dev/ | |
310 | with a name starting | |
311 | .B md | |
312 | or | |
313 | .BR md_ . | |
314 | Give | |
16c4849b | 315 | .B symlinks=no |
38098016 | 316 | to suppress this symlink creation. |
5bbb4842 NB |
317 | .RE |
318 | ||
6d6de2ee NB |
319 | .TP |
320 | .B HOMEHOST | |
321 | The | |
322 | .B homehost | |
323 | line gives a default value for the | |
324 | .B --homehost= | |
325 | option to mdadm. There should be exactly one other word on the line. | |
326 | It should either exactly | |
327 | .B <system> | |
328 | or a host name. | |
329 | If | |
330 | .B <system> | |
331 | is given, then the | |
332 | .BR gethostname ( 2 ) | |
333 | systemcall is used to get the host name. | |
334 | When arrays are created, this host name will be stored in the | |
335 | metadata. When arrays are assembled using auto-assembly, only arrays | |
336 | with this host name stored in the metadata will be considered. | |
5bbb4842 | 337 | |
2d465520 NB |
338 | .SH EXAMPLE |
339 | DEVICE /dev/sd[bcdjkl]1 | |
340 | .br | |
341 | DEVICE /dev/hda1 /dev/hdb1 | |
342 | ||
0e69da72 | 343 | # /dev/md0 is known by its UUID. |
2d465520 NB |
344 | .br |
345 | ARRAY /dev/md0 UUID=3aaa0122:29827cfa:5331ad66:ca767371 | |
346 | .br | |
347 | # /dev/md1 contains all devices with a minor number of | |
348 | .br | |
349 | # 1 in the superblock. | |
350 | .br | |
351 | ARRAY /dev/md1 superminor=1 | |
352 | .br | |
93e790af | 353 | # /dev/md2 is made from precisely these two devices |
2d465520 | 354 | .br |
a9d69660 | 355 | ARRAY /dev/md2 devices=/dev/hda1,/dev/hdb1 |
2d465520 NB |
356 | |
357 | # /dev/md4 and /dev/md5 are a spare-group and spares | |
358 | .br | |
359 | # can be moved between them | |
360 | .br | |
361 | ARRAY /dev/md4 uuid=b23f3c6d:aec43a9f:fd65db85:369432df | |
362 | .br | |
7e23fc43 | 363 | spare\-group=group1 |
2d465520 NB |
364 | .br |
365 | ARRAY /dev/md5 uuid=19464854:03f71b1b:e0df2edd:246cc977 | |
366 | .br | |
7e23fc43 | 367 | spare\-group=group1 |
dd0781e5 NB |
368 | .br |
369 | # /dev/md/home is created if need to be a partitionable md array | |
370 | .br | |
371 | # any spare device number is allocated. | |
372 | .br | |
373 | ARRAY /dev/md/home UUID=9187a482:5dde19d9:eea3cc4a:d646ab8b | |
374 | .br | |
375 | auto=part | |
2d465520 NB |
376 | |
377 | MAILADDR root@mydomain.tld | |
378 | .br | |
7e23fc43 | 379 | PROGRAM /usr/sbin/handle\-mdadm\-events |
5bbb4842 | 380 | .br |
7e23fc43 | 381 | CREATE group=system mode=0640 auto=part\-8 |
41a3b72a NB |
382 | .br |
383 | HOMEHOST <system> | |
e0d19036 | 384 | |
56eb10c0 | 385 | .SH SEE ALSO |
11a3e71d NB |
386 | .BR mdadm (8), |
387 | .BR md (4). | |
56eb10c0 | 388 |