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1 perry 1 TUNE2FS
2 !!!TUNE2FS
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 OPTIONS
7 BUGS
8 AUTHOR
9 AVAILABILITY
10 SEE ALSO
11 ----
12 !!NAME
13
14
15 tune2fs - adjust tunable filesystem parameters on second extended filesystems
16 !!SYNOPSIS
17
18
19 __tune2fs__ [[ __-l__ ] [[ __-c__
20 ''max-mount-counts'' ] [[ __-e__ ''errors-behavior''
21 ] [[ __-f__ ] [[ __-i__ ''interval-between-checks'' ]
22 [[ __-j__ ] [[ __-J__ ''journal-options'' ] [[
23 __-m__ ''reserved-blocks-percentage'' ] [[ __-r__
24 ''reserved-blocks-count'' ] [[ __-s__
25 ''sparse-super-flag'' ] [[ __-u__ ''user'' ] [[
26 __-g__ ''group'' ] [[ __-C__ ''mount-count'' ] [[
27 __-L__ ''volume-name'' ] [[ __-M__
28 ''last-mounted-directory'' ] [[ __-O__
29 [[^]''feature''[[,...] ] [[ __-T__
30 ''time-last-checked'' ] [[ __-U__ ''UUID'' ]
31 device
32 !!DESCRIPTION
33
34
35 __tune2fs__ adjusts tunable filesystem parameters on a
36 Linux second extended filesystem.
37 !!OPTIONS
38
39
40 __-c__ ''max-mount-counts''
41
42
43 Adjust the maximal mounts count between two filesystem
44 checks. If ''max-mount-counts'' is 0 then the number of
45 times the filesystem is mounted will be disregarded by
2 perry 46 e2fsck(8) and the kernel.
1 perry 47
48
49 Staggering the mount-counts at which filesystems are
50 forcibly checked will avoid all filesystems being checked at
51 one time when using journaled filesystems.
52
53
54 You should strongly consider the consequences of disabling
55 mount-count-dependent checking entirely. Bad disk drives,
56 cables, memory, and kernel bugs could all corrupt a
57 filesystem without marking the filesystem dirty or in error.
58 If you are using journaling on your filesystem, your
59 filesystem will __never__ be marked dirty, so it will not
60 normally be checked. A filesystem error detected by the
61 kernel will still force an fsck on the next reboot, but it
62 may already be too late to prevent data loss at that
63 point.
64
65
66 See also the __-i__ option for time-dependent
67 checking.
68
69
70 __-C__ ''mount-count''
71
72
73 Set the number of times the filesystem has been mounted. Can
74 be used in conjunction with -c to force an fsck on the
75 filesystem at the next reboot.
76
77
78 __-e__ ''error-behavior''
79
80
81 Change the behavior of the kernel code when errors are
82 detected. In all cases, a filesystem error will cause
2 perry 83 e2fsck(8) to check the filesystem on the next boot.
1 perry 84 ''error-behavior'' can be one of the
85 following:
86
87
88 __continue__
89
90
91 Continue normal execution.
92
93
94 __remount-ro__
95
96
97 Remount filesystem read-only.
98
99
100 __panic__
101
102
103 Cause a kernel panic.
104
105
106 __-f__
107
108
109 Force the tune2fs operation to complete even in the face of
110 errors. This option is useful when removing the
111 __has_journal__ filesystem feature from a filesystem
112 which has an external journal (or is corrupted such that it
113 appears to have an external journal), but that external
114 journal is not available.
115
116
117 __WARNING:__ Removing an external journal from a
118 filesystem which was not cleanly unmounted without first
119 replaying the external journal can result in severe data
120 loss and filesystem corruption.
121
122
123 __-g__ ''group''
124
125
126 Set the group which can use reserved filesystem blocks. The
127 ''group'' parameter can be a numerical gid or a group
128 name. If a group name is given, it is converted to a
129 numerical gid before it is stored in the
130 superblock.
131
132
133 __-i__
134 ''interval-between-checks''[[__d__|__m__|__w__]
135
136
137 Adjust the maximal time between two filesystem checks. No
138 postfix or __d__ result in days, __m__ in months, and
139 __w__ in weeks. A value of zero will disable the
140 time-dependent checking.
141
142
143 It is strongly recommended that either __-c__
144 (mount-count-dependent) or __-i__ (time-dependent)
2 perry 145 checking be enabled to force periodic full e2fsck(8)
1 perry 146 checking of the filesystem. Failure to do so may lead to
147 filesystem corruption due to bad disks, cables, memory, or
148 kernel bugs to go unnoticed until they cause data loss or
149 corruption.
150
151
152 __-j__
153
154
155 Add an ext3 journal to the filesystem. If the __-J__
156 option is not specified, the default journal parameters will
157 be used to create an appropriately sized journal (given the
158 size of the filesystem) stored within the filesystem. Note
159 that you must be using a kernel which has ext3 support in
160 order to actually make use of the journal.
161
162
163 __-J__ journal-options
164
165
166 Override the default ext3 journal parameters. Journal
167 options are comma separated, and may take an argument using
168 the equals ('=') sign. The following journal options are
169 supported:
170
171
172 __size=__''journal-size''
173
174
175 Create a journal stored in the filesystem of size
176 ''journal-size'' megabytes. The size of the journal must
177 be at least 1024 filesystem blocks (i.e., 1MB if using 1k
178 blocks, 4MB if using 4k blocks, etc.) and may be no more
179 than 102,400 filesystem blocks. There must be enough free
180 space in the filesystem to create a journal of that
181 size.
182
183
184 __device=__''external-journal''
185
186
187 Attach the filesystem to the journal block device located on
188 ''external-journal''. The external journal must have been
189 already created using the command
190
191
192 __mke2fs -O journal_dev__
193 ''external-journal''
194
195
196 Note that ''external-journal'' must be formatted with the
197 same block size as filesystems which will be using
198 it.
199
200
201 Instead of specifying a device name directly,
202 ''external-journal'' can also be specified by either
203 __LABEL=__''label'' or __UUID=__''UUID'' to
204 locate the external journal by either the volume label or
205 UUID stored in the ext2 superblock at the start of the
2 perry 206 journal. Use dumpe2fs(8) to display a journal
1 perry 207 device's volume label and UUID. See also the __-L__
2 perry 208 option of tune2fs(8).
1 perry 209
210
211 Only one of the __size__ or __device__ options can be
212 given for a filesystem.
213
214
215 __-l__
216
217
218 List the contents of the filesystem superblock.
219
220
221 __-L__ ''volume-label''
222
223
224 Set the volume label of the filesystem. Ext2 filesystem
225 labels can be at most 16 characters long; if
226 ''volume-label'' is longer than 16 characters,
227 __tune2fs__ will truncate it and print a warning. The
228 volume label can be used by mount(8), fsck(8),
2 perry 229 and /etc/fstab(5) (and possibly others) by specifying
1 perry 230 __LABEL=__''volume_label'' instead of a block special
231 device name like __/dev/hda5__.
232
233
234 __-m__ ''reserved-blocks-percentage''
235
236
237 Set the percentage of reserved filesystem
238 blocks.
239
240
241 __-M__ ''last-mounted-directory''
242
243
244 Set the last-mounted directory for the
245 filesystem.
246
247
248 __-O__ [[^]''feature''[[,...]
249
250
251 Set or clear the indicated filesystem features (options) in
252 the filesystem. More than one filesystem feature can be
253 cleared or set by separating features with commas.
254 Filesystem features prefixed with a caret character ('^')
255 will be cleared in the filesystem's superblock; filesystem
256 features without a prefix character or prefixed with a plus
257 character ('+') will be added to the
258 filesystem.
259
260
261 The following filesystem features can be set or cleared
262 using __tune2fs__:
263
264
265 __sparse_super__
266
267
268 Limit the number of backup superblocks to save space on
269 large filesystems.
270
271
272 __filetype__
273
274
275 Store file type information in directory
276 entries.
277
278
279 __has_journal__
280
281
282 Create an ext3 journal (as if using the __-j__
283 option).
284
285
286 After setting or clearing __sparse_super__ and
2 perry 287 __filetype__ filesystem features, e2fsck(8) must
1 perry 288 be run on the filesystem to return the filesystem to a
289 consistent state. __Tune2fs__ will print a message
290 requesting that the system administrator run
2 perry 291 e2fsck(8) if necessary.
1 perry 292
293
294 __Warning:__ Linux kernels before 2.0.39 and many 2.1
295 series kernels do not support the filesystems that use any
296 of these features. Enabling certain filesystem features may
297 prevent the filesystem from being mounted by kernels which
298 do not support those features.
299
300
301 __-r__ ''reserved-blocks-count''
302
303
304 Set the number of reserved filesystem blocks.
305
306
307 __-s__ [[__0__|__1__]
308
309
310 Turn the sparse super feature off or on. Turning this
311 feature on saves space on really big filesystems. This is
312 the same as using the __-O sparse_super__
313 option.
314
315
316 __Warning:__ Linux kernels before 2.0.39 do not support
317 this feature. Neither do all Linux 2.1 kernels; please don't
318 use this unless you know what you're doing! You need to run
2 perry 319 e2fsck(8) on the filesystem after changing this
1 perry 320 feature in order to have a valid filesystem.
321
322
323 __-T__ ''time-last-checked''
324
325
326 Set the time the filesystem was last checked using
327 __e2fsck__. This can be useful in scripts which use a
328 Logical Volume Manager to make a consistent snapshot of a
329 filesystem, and then check the filesystem during off hours
330 to make sure it hasn't been corrupted due to hardware
331 problems, etc. If the filesystem was clean, then this option
332 can be used to set the last checked time on the original
333 filesystem. The format of ''time-last-checked'' is the
334 international date format, with an optional time specifier,
335 i.e. YYYYMMDD[[[[HHMM]SS]. The keyword __now__ is also
336 accepted, in which case the last checked time will be set to
337 the current time.
338
339
340 __-u__ ''user''
341
342
343 Set the user who can use the reserved filesystem blocks.
344 ''user'' can be a numerical uid or a user name. If a user
345 name is given, it is converted to a numerical uid before it
346 is stored in the superblock.
347
348
349 __-U__ ''UUID''
350
351
352 Set the universally unique identifier (UUID) of the
353 filesystem to ''UUID''. The format of the UUID is a
354 series of hex digits separated by hypthens, like this:
355 ''UUID'' parameter may also be one of the
356 following:
357
358
359 ''clear''
360
361
362 clear the filesystem UUID
363
364
365 ''random''
366
367
368 generate a new randomly-generated UUID
369
370
371 ''time''
372
373
374 generate a new time-based UUID
375
376
377 The UUID may be used by mount(8), fsck(8), and
2 perry 378 /etc/fstab(5) (and possibly others) by specifying
1 perry 379 __UUID=__''uuid'' instead of a block special device
380 name like __/dev/hda1__.
381
382
383 See uuidgen(8) for more information. If the system
384 does not have a good random number generator such as
385 ''/dev/random'' or ''/dev/urandom'', __tune2fs__
386 will automatically use a time-based UUID instead of a
387 randomly-generated UUID.
388 !!BUGS
389
390
391 We haven't found any bugs yet. That doesn't mean there
392 aren't any...
393 !!AUTHOR
394
395
396 __tune2fs__ was written by Remy Card
397 __tune2fs__ uses the ext2fs
398 library written by Theodore Ts'o
399 __
400 !!AVAILABILITY
401
402
403 __tune2fs__ is part of the e2fsprogs package and is
404 available from
405 http://e2fsprogs.sourceforge.net.
406 !!SEE ALSO
407
408
2 perry 409 dumpe2fs(8), __e2fsck__(8),
410 mke2fs(8)
1 perry 411 ----
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