1mkfs.ocfs2(8) OCFS2 Manual Pages mkfs.ocfs2(8)
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6 mkfs.ocfs2 - Creates an OCFS2 file system.
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9 mkfs.ocfs2 [-b block-size] [-C cluster-size] [-L volume-label] [-M
10 mount-type] [-N number-of-nodes] [-J journal-options] [--fs-fea‐
11 tures=[no]sparse...] [--fs-feature-level=feature-level] [-T filesys‐
12 tem-type] [--cluster-stack=stackname] [--cluster-name=clustername]
13 [--global-heartbeat] [-FqvV] device [blocks-count]
14
16 mkfs.ocfs2 is used to create an OCFS2 file system on a device, usually
17 a partition on a shared disk. In order to prevent data loss, mkfs.ocfs2
18 will not format an existing OCFS2 volume if it detects that it is
19 mounted on another node in the cluster. This tool requires the cluster
20 service to be online.
21
24 -b, --block-size block-size
25 Valid block size values are 512, 1K, 2K and 4K bytes per block.
26 If omitted, a value will be heuristically determined based on
27 the expected usage of the file system (see the -T option). A
28 block size of 512 bytes is never recommended. Choose 1K, 2K or
29 4K.
30 -C, --cluster-size cluster-size
33 Valid cluster size values are 4K, 8K, 16K, 32K, 64K, 128K, 256K,
34 512K and 1M. If omitted, a value will be heuristically deter‐
35 mined based on the expected usage of the file system (see the -T
36 option). For volumes expected to store large files, like data‐
37 base files, while a cluster size of 128K or more is recommended,
38 one can opt for a smaller size as long as that value is not
39 smaller than the database block size. For others, use 4K.
40 -F, --force
43 For existing OCFS2 volumes, mkfs.ocfs2 ensures the volume is not
44 mounted on any node in the cluster before formatting. For that
45 to work, mkfs.ocfs2 expects the cluster service to be online.
46 Specify this option to disable this check.
47 -J, --journal-options options
50 Create the journal using options specified on the command-line.
51 Journal options are comma separated, and may take an argument
52 using the equals ('=') sign. The following options are sup‐
53 ported:
54 size=journal-size
57 Create a journal of size journal-size. Minimum size is
58 4M. If omitted, a value is heuristically determined
59 based upon the file system size.
60 block32
63 Use a standard 32bit journal. The journal will be able
64 to access up to 2^32-1 blocks. This is the default. It
65 has been the journal format for OCFS2 volumes since the
66 beginning. The journal is compatible with all versions
67 of OCFS2. Prepending no is equivalent to the block64
68 journal option.
69 block64
72 Use a 64bit journal. The journal will be able to access
73 up to 2^64-1 blocks. This allows large filesystems that
74 can extend to the theoretical limits of OCFS2. It
75 requires a new-enough filesystem driver that uses the new
76 journalled block device, JBD2. Prepending no is equiva‐
77 lent to the block32 journal option.
78 -L, --label volume-label
81 Set the volume label for the file system. This is useful for
82 mounting-by-label. Limit the label to under 64 bytes.
83 -M, --mount mount-type
86 Valid types are local and cluster. Local mount allows users to
87 mount the volume without the cluster overhead and works only
88 with OCFS2 bundled with Linux kernels 2.6.20 or later. Defaults
89 to cluster.
90 -N, --node-slots number-of-node-slots
93 Valid number ranges from 1 to 255. This number specifies the
94 maximum number of nodes that can concurrently mount the parti‐
95 tion. If omitted, the number depends on volume size, for volume
96 size < 2G, it's 2, for 2G <= size < 10G, it's 4, for 10G <= size
97 < 1T, it's 8, for other size, it's 16. The number of slots can
98 be later tuned up or down using tunefs.ocfs2.
99 -T filesystem-type
102 Specify how the filesystem is going to be used, so that
103 mkfs.ocfs2 can chose optimal filesystem parameters for that use.
104 The supported filesystem types are:
105 mail Appropriate for file systems that will host lots of small
108 files.
109 datafiles
112 Appropriate for file systems that will host a relatively
113 small number of very large files.
114 vmstore
117 Appropriate for file systems that will host Virtual
118 machine images.
119 --fs-features=[no]sparse...
122 Turn specific file system features on or off. A comma separated
123 list of feature flags can be provided, and mkfs.ocfs2 will try
124 to create the file system with those features set according to
125 the list. To turn a feature on, include it in the list. To turn
126 a feature off, prepend no to the name. Choices here will over‐
127 ride individual features set via the --fs-feature-level option.
128 Refer to the section titled feature compatibility before select‐
129 ing specific features. The following flags are supported:
130 backup-super
133 mkfs.ocfs2, by default, makes up to 6 backup copies of
134 the super block at offsets 1G, 4G, 16G, 64G, 256G and 1T
135 depending on the size of the volume. This can be useful
136 in disaster recovery. This feature is fully compatible
137 with all versions of the file system and generally should
138 not be disabled.
139 local Create the file system as a local mount, so that it can
142 be mounted without a cluster stack.
143 sparse Enable support for sparse files. With this, OCFS2 can
146 avoid allocating (and zeroing) data to fill holes. Turn
147 this feature on if you can, otherwise extends and some
148 writes might be less performant.
149 unwritten
152 Enable unwritten extents support. With this turned on, an
153 application can request that a range of clusters be pre-
154 allocated within a file. OCFS2 will mark those extents
155 with a special flag so that expensive data zeroing
156 doesn't have to be performed. Reads and writes to a pre-
157 allocated region act as reads and writes to a hole,
158 except a write will not fail due to lack of data alloca‐
159 tion. This feature requires sparse file support to be
160 turned on.
161 inline-data
164 Enable inline-data support. If this feature is turned on,
165 OCFS2 will store small files and directories inside the
166 inode block. Data is transparently moved out to an extent
167 when it no longer fits inside the inode block. In some
168 cases, this can also make a positive impact on cold-cache
169 directory and file operations.
170 extended-slotmap
173 The slot-map is a hidden file on an OCFS2 fs which is
174 used to map mounted nodes to system file resources. The
175 extended slot map allows a larger range of possible node
176 numbers, which is useful for userspace cluster stacks. If
177 required, this feature is automatically turned on by
178 mkfs.ocfs2.
179 metaecc
182 Enables metadata checksums. With this enabled, the file
183 system computes and stores the checksums in all metadata
184 blocks. It also computes and stores an error correction
185 code capable of fixing single bit errors.
186 refcount
189 Enables creation of reference counted trees. With this
190 enabled, the file system allows users to create inode-
191 based snapshots and clones known as reflinks.
192 xattr Enable extended attributes support. With this enabled,
195 users can attach name:value pairs to objects within the
196 file system. In OCFS2, the names can be upto 255 bytes in
197 length, terminated by the first NUL byte. While it is not
198 required, printable names (ASCII) are recommended. The
199 values can be upto 64KB of arbitrary binary data.
200 Attributes can be attached to all types of inodes: regu‐
201 lar files, directories, symbolic links, device nodes,
202 etc. This feature is required for users wanting to use
203 extended security facilities like POSIX ACLs or SELinux.
204 usrquota
207 Enable user quota support. With this feature enabled,
208 filesystem will track amount of space and number of
209 inodes (files, directories, symbolic links) each user
210 owns. It is then possible to limit the maximum amount of
211 space or inodes user can have. See a documentation of
212 quota-tools package for more details.
213 grpquota
216 Enable group quota support. With this feature enabled,
217 filesystem will track amount of space and number of
218 inodes (files, directories, symbolic links) each group
219 owns. It is then possible to limit the maximum amount of
220 space or inodes user can have. See a documentation of
221 quota-tools package for more details.
222 indexed-dirs
225 Enable directory indexing support. With this feature
226 enabled, the file system creates indexed tree for non-
227 inline directory entries. For large scale directories,
228 directory entry lookup perfromance from the indexed tree
229 is faster then from the legacy directory blocks.
230 discontig-bg
233 Enables discontiguous block groups. With this feature
234 enabled, the file system is able to grow the inode and
235 the extent allocators even when there is no contiguous
236 free chunk available. It allows the file system to grow
237 the allocators in smaller (discontiguous) chunks.
238 clusterinfo
241 Enables storing the cluster stack information in the
242 superblock. This feature is needed to support userspace
243 cluster stacks and the global heartbeat mode in the o2cb
244 cluster stack. If needed, this feature is automatically
245 turned on by mkfs.ocfs2.
246 --fs-feature-level=feature-level
249 Choose from a set of pre-determined file-system features. This
250 option is designed to allow users to conveniently choose a set
251 of file system features which fits their needs. There is no
252 downside to trying a set of features which your module might not
253 support - if it won't mount the new file system simply reformat
254 at a lower level. Feature levels can be fine-tuned via the
255 --fs-features option. Currently, there are 3 types of feature
256 levels:
257 max-compat
260 Chooses fewer features but ensures that the file system
261 can be mounted from older versions of the OCFS2 module.
262 default
265 The default feature set tries to strike a balance between
266 providing new features and maintaining compatibility with
267 relatively recent versions of OCFS2. It currently enables
268 sparse, unwritten, inline-data, xattr, indexed-dirs, dis‐
269 contig-bg, refcount, extended-slotmap and clusterinfo.
270 max-features
273 Choose the maximum amount of features available. This
274 will typically provide the best performance from OCFS2 at
275 the expense of creating a file system that is only com‐
276 patible with very recent versions of the OCFS2 kernel
277 module.
278 --cluster-stack
281 Specify the cluster stack. This option is normally not required
282 as mkfs.ocfs2 chooses the currently active cluster stack. It is
283 required only if the cluster stack is not online and the user
284 wishes to use a stack other than the default, o2cb. Other sup‐
285 ported cluster stacks are pcmk (Pacemaker) and cman (rgmanager).
286 Once set, OCFS2 will only allow mounting the volume if the
287 active cluster stack and cluster name matches the one specified
288 on-disk.
289 --cluster-name
292 Specify the name of the cluster. This option is mandatory if the
293 user has specified a cluster-stack. This name is restricted to a
294 max of 16 characters. Additionally, the o2cb cluster stack
295 allows only alpha-numeric characters.
296 --global-heartbeat
299 Enable the global heartbeat mode of the o2cb cluster stack. This
300 option is not required if the o2cb cluster stack with global
301 heartbeat is online as mkfs.ocfs2 will detect the active stack.
302 However, if the cluster stack is not up, then this option is
303 required alongwith cluster-stack and cluster-name. For more,
304 refer to o2cb(7).
305 --no-backup-super
308 This option is deprecated, please use --fs-features=nobackup-
309 super instead.
310 -n, --dry-run
313 Display the heuristically determined values without overwriting
314 the existing file system.
315 -q, --quiet
318 Quiet mode.
319 -U uuid
322 Specify a custom UUID in the plain
323 (2A4D1C581FAA42A1A41D26EFC90C1315) or traditional
324 (2a4d1c58-1faa-42a1-a41d-26efc90c1315) format. This option in
325 not recommended because the file system uses the UUID to
326 uniquely identify a file system. If more than one file system
327 were to have the same UUID, one is very likely to encounter
328 erratic behavior, if not, outright file system corruption.
329 -v, --verbose
332 Verbose mode.
333 -V, --version
336 Print version and exit.
337 blocks-count
340 Usually mkfs.ocfs2 automatically determines the size of the
341 given device and creates a file system that uses all of the
342 available space on the device. This optional argument specifies
343 that the file system should only consume the given number of
344 file system blocks (see -b) on the device.
345
348 This section lists the file system features that have been added to the
349 OCFS2 file system and the version that it first appeared in. The table
350 below lists the versions of the mainline Linux kernel and ocfs2-tools.
351 Users should use this information to enable only those features that
352 are available in the file system that they are using. Before enabling
353 new features, users are advised to review to the section titled feature
354 values.
355 ┌─────────────────┬────────────────┬─────────────────┐
358 │Feature │ Kernel Version │ Tools Version │
359 ├─────────────────┼────────────────┼─────────────────┤
360 │local │ Linux 2.6.20 │ ocfs2-tools 1.2 │
361 ├─────────────────┼────────────────┼─────────────────┤
362 │sparse │ Linux 2.6.22 │ ocfs2-tools 1.4 │
363 ├─────────────────┼────────────────┼─────────────────┤
364 │unwritten │ Linux 2.6.23 │ ocfs2-tools 1.4 │
365 ├─────────────────┼────────────────┼─────────────────┤
366 │inline-data │ Linux 2.6.24 │ ocfs2-tools 1.4 │
367 ├─────────────────┼────────────────┼─────────────────┤
368 │extended-slotmap │ Linux 2.6.27 │ ocfs2-tools 1.6 │
369 ├─────────────────┼────────────────┼─────────────────┤
370 │metaecc │ Linux 2.6.29 │ ocfs2-tools 1.6 │
371 ├─────────────────┼────────────────┼─────────────────┤
372 │grpquota │ Linux 2.6.29 │ ocfs2-tools 1.6 │
373 ├─────────────────┼────────────────┼─────────────────┤
374 │usrquota │ Linux 2.6.29 │ ocfs2-tools 1.6 │
375 ├─────────────────┼────────────────┼─────────────────┤
376 │xattr │ Linux 2.6.29 │ ocfs2-tools 1.6 │
377 ├─────────────────┼────────────────┼─────────────────┤
378 │indexed-dirs │ Linux 2.6.30 │ ocfs2-tools 1.6 │
379 ├─────────────────┼────────────────┼─────────────────┤
380 │refcount │ Linux 2.6.32 │ ocfs2-tools 1.6 │
381 ├─────────────────┼────────────────┼─────────────────┤
382 │discontig-bg │ Linux 2.6.35 │ ocfs2-tools 1.6 │
383 ├─────────────────┼────────────────┼─────────────────┤
384 │clusterinfo │ Linux 2.6.37 │ ocfs2-tools 1.8 │
385 └─────────────────┴────────────────┴─────────────────┘
386 Users can query the features enabled in the file system as follows:
388 # tunefs.ocfs2 -Q "Label: %V\nFeatures: %H %O\n" /dev/sdg1
390 Label: apache_files_10
391 Features: sparse inline-data unwritten
392
395 This section lists the hex values that are associated with the file
396 system features. This information is useful when debugging mount fail‐
397 ures that are due to feature incompatibility. When a user attempts to
398 mount an OCFS2 volume that has features enabled that are not supported
399 by the running file system software, it will fail with an error like:
400 ERROR: couldn't mount because of unsupported optional features (200).
402 By referring to the table below, it becomes apparent that the user
404 attempted to mount a volume with the xattr (extended attributes) fea‐
405 ture enabled with a version of the file system software that did not
406 support it. At this stage, the user has the option of either upgrading
407 the file system software, or, disabling that on-disk feature using
408 tunefs.ocfs2.
409 Some features allow the file system to be mounted with an older version
411 of the software provided the mount is read-only. If a user attempts to
412 mount such a volume in a read-write mode, it will fail with an error
413 like:
414 ERROR: couldn't mount RDWR because of unsupported optional features (1).
416 This error indicates that the volume had the unwritten RO compat fea‐
418 ture enabled. This volume can be mounted by an older file system soft‐
419 ware only in the read-only mode. In this case, the user has the option
420 of either mounting the volume with the ro mount option, or, disabling
421 that on-disk feature using tunefs.ocfs2.
422 ┌─────────────────┬───────────┬───────────┐
425 │Feature │ Category │ Hex value │
426 ├─────────────────┼───────────┼───────────┤
427 │local │ Incompat │ 8 │
428 ├─────────────────┼───────────┼───────────┤
429 │sparse │ Incompat │ 10 │
430 ├─────────────────┼───────────┼───────────┤
431 │inline-data │ Incompat │ 40 │
432 ├─────────────────┼───────────┼───────────┤
433 │extended-slotmap │ Incompat │ 100 │
434 ├─────────────────┼───────────┼───────────┤
435 │xattr │ Incompat │ 200 │
436 ├─────────────────┼───────────┼───────────┤
437 │indexed-dirs │ Incompat │ 400 │
438 ├─────────────────┼───────────┼───────────┤
439 │metaecc │ Incompat │ 800 │
440 ├─────────────────┼───────────┼───────────┤
441 │refcount │ Incompat │ 1000 │
442 ├─────────────────┼───────────┼───────────┤
443 │discontig-bg │ Incompat │ 2000 │
444 ├─────────────────┼───────────┼───────────┤
445 │clusterinfo │ Incompat │ 4000 │
446 ├─────────────────┼───────────┼───────────┤
447 │unwritten │ RO Compat │ 1 │
448 ├─────────────────┼───────────┼───────────┤
449 │usrquota │ RO Compat │ 2 │
450 ├─────────────────┼───────────┼───────────┤
451 │grpquota │ RO Compat │ 4 │
452 └─────────────────┴───────────┴───────────┘
453
456 debugfs.ocfs2(8) fsck.ocfs2(8) mount.ocfs2(8) mounted.ocfs2(8) o2cb(7)
457 o2cluster(8) o2image(8) o2info(1) tunefs.ocfs2(8)
458
461 Oracle Corporation
462
465 Copyright © 2004, 2012 Oracle. All rights reserved.
466Version 1.8.5 January 2012 mkfs.ocfs2(8)