2 .\" Copyright 1993, 1994, 1995 by Theodore Ts'o. All Rights Reserved.
3 .\" This file may be copied under the terms of the GNU Public License.
5 .TH MKE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
7 mke2fs \- create an ext2/ext3 filesystem
48 .I reserved-blocks-percentage
81 .I last-mounted-directory
98 @JDEV@.B "mke2fs \-O journal_dev"
103 .\" No external-journal specific journal options yet (size is ignored)
106 .\" @JDEV@.I journal-options
110 @JDEV@.I volume-label
121 @JDEV@.I external-journal
123 @JDEV@.I blocks-count
127 is used to create an ext2/ext3 filesystem (usually in a disk partition).
129 is the special file corresponding to the device (e.g
132 is the number of blocks on the device. If omitted,
134 automagically figures the file system size. If called as
136 a journal is created as if the
138 option was specified.
141 .BI \-b " block-size"
142 Specify the size of blocks in bytes. Valid block size vales are 1024,
143 2048 and 4096 bytes per block. If omitted,
145 block-size is heuristically determined by the file system size and
146 the expected usage of the filesystem (see the
150 is negative, then mke2fs will use heuristics to determine the
151 appropriate block size, with the constraint that the block size will be
154 bytes. This is useful for certain hardware devices which require that
155 the blocksize be a multiple of 2k.
158 Check the device for bad blocks before creating the file system. If
159 this option is specified twice, then a slower, read-write
160 test is used instead of a fast read-only test.
162 .BI \-f " fragment-size"
163 Specify the size of fragments in bytes.
168 to run, even if the specified device is not a
169 block special device, or appears to be mounted.
171 .BI \-g " blocks-per-group"
172 Specify the number of blocks in a block group. There is generally no
173 reason the user to ever set this parameter, as the default is optimal
174 for the filesystem. (For administrators who are creating
175 filesystems on RAID arrays, it is preferable to use the
177 RAID parameter as part of the
179 option rather than manipulating the number of blocks per group.)
180 This option is generally used by developers who
181 are developing test cases.
183 .BI \-i " bytes-per-inode"
184 Specify the bytes/inode ratio.
186 creates an inode for every
188 bytes of space on the disk. The larger the
190 ratio, the fewer inodes will be created. This value generally shouldn't
191 be smaller than the blocksize of the filesystem, since then too many
192 inodes will be made. Be warned that is not possible to expand the number
193 of inodes on a filesystem after it is created, so be careful deciding the
194 correct value for this parameter.
197 Create the filesystem with an ext3 journal. If the
199 option is not specified, the default journal parameters will be used to
200 create an appropriately sized journal (given the size of the filesystem)
201 stored within the filesystem. Note that you must be using a kernel
202 which has ext3 support in order to actually make use of the journal.
204 .BI \-J " journal-options"
205 Create the ext3 journal using options specified on the command-line.
206 Journal options are comma
207 separated, and may take an argument using the equals ('=') sign.
208 The following journal options are supported:
211 .BI size= journal-size
212 Create an internal journal (i.e., stored inside the filesystem) of size
215 The size of the journal must be at least 1024 filesystem blocks
216 (i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.)
217 and may be no more than 102,400 filesystem blocks.
219 @JDEV@.BI device= external-journal
220 @JDEV@Attach the filesystem to the journal block device located on
221 @JDEV@.IR external-journal .
223 @JDEV@journal must already have been created using the command
225 @JDEV@.B mke2fs -O journal_dev
226 @JDEV@.I external-journal
229 @JDEV@.I external-journal
230 @JDEV@must have been created with the
231 @JDEV@same block size as the new filesystem.
233 @JDEV@Instead of specifying a device name directly,
234 @JDEV@.I external-journal
235 @JDEV@can also be specified by either
236 @JDEV@.BI LABEL= label
239 @JDEV@to locate the external journal by either the volume label or UUID
240 @JDEV@stored in the ext2 superblock at the start of the journal. Use
241 @JDEV@.BR dumpe2fs (8)
242 @JDEV@to display a journal device's volume label and UUID. See also the
245 @JDEV@.BR tune2fs (8).
248 @JDEV@Only one of the
249 @JDEV@.BR size " or " device
250 @JDEV@options can be given for a filesystem.
253 Read the bad blocks list from
255 Note that the block numbers in the bad block list must be generated
256 using the same block size as used by mke2fs. As a result, the
260 is a much simpler and less error-prone method of checking a disk for bad
261 blocks before formatting it, as
263 will automatically pass the correct parameters to the
268 Set the volume label for the filesystem.
270 .BI \-m " reserved-blocks-percentage"
271 Specify the percentage of the filesystem blocks reserved for
272 the super-user. This avoids fragmentation, and allows root-owned
275 to continue to function correctly after non-privileged processes are
276 prevented from writing to the filesystem. The default percentage
280 Set the last mounted directory for the filesystem. This might be useful
281 for the sake of utilities that key off of the last mounted directory to
282 determine where the filesytem should be mounted.
285 causes mke2fs to not actually create a filesystem, but display what it
286 would do if it were to create a filesystem. This can be used to
287 determine the location of the backup superblocks for a particular
288 filesystem, so long as the mke2fs parameters that were passed when the
289 filesystem was originally created are used again. (With the
291 option added, of course!)
293 .BI \-N " number-of-inodes"
294 overrides the default calculation of the number of inodes that should be
295 reserved for the filesystem (which is based on the number of blocks and
298 ratio). This allows the user to specify the number
299 of desired inodes directly.
301 .BI \-o " creator-os"
302 Manually override the default value of the "creator os" field of the
303 filesystem. Normally the creator field is set by default to the native OS
308 .B "\-O \fIfeature\fR[,...]"
309 Create filesystem with given features (filesystem options), overriding
310 the default filesystem options.
315 features are turned on by default when
317 is run on a system with Linux 2.2 or later (unless creator-os is set to
318 the Hurd). Filesystems that may need to be mounted on pre-2.2 Linux or
319 other kernels should be created with
323 for Linux 1.2) which will disable these features, even if
325 is run on a system which can support them.
327 The following filesystem options are supported:
331 Use hashed b-trees to speed up lookups in large directories.
334 Store file type information in directory entries.
337 Create an ext3 journal (as if using the
342 @JDEV@Create an external ext3 journal on the given device
343 @JDEV@instead of a regular ext2 filesystem.
345 @JDEV@.I external-journal
346 @JDEV@must be created with the same
347 @JDEV@block size as the filesystems that will be using it.
350 Create a filesystem with fewer superblock backup copies
351 (saves space on large filesystems).
355 Quiet execution. Useful if
360 Set the filesystem revision for the new filesystem. Note that 1.2
361 kernels only support revision 0 filesystems. The default is to
362 create revision 1 filesystems.
364 .BI \-R " raid-options"
365 Set raid-related options for the filesystem. Raid options are comma
366 separated, and may take an argument using the equals ('=') sign. The
367 following options are supported:
370 .BI stride= stripe-size
371 Configure the filesystem for a RAID array with
373 filesystem blocks per stripe.
377 Write superblock and group descriptors only. This is useful if all of
378 the superblock and backup superblocks are corrupted, and a last-ditch
379 recovery method is desired. It causes
382 superblock and group descriptors, while not touching the inode table
383 and the block and inode bitmaps. The
385 program should be run immediately after this option is used, and there
386 is no guarantee that any data will be salvageable. It is critical to
387 specify the correct filesystem blocksize when using this option,
388 or there is no chance of recovery.
391 .\" Check the device for bad blocks before creating the file system
392 .\" using the specified test.
395 Specify how the filesystem is going to be used, so that mke2fs can
396 chose optimal filesystem parameters for that use. The supported
397 filesystem types are:
401 one inode per 4kb block
404 one inode per megabyte
407 one inode per 4 megabytes
414 Print the version number of
420 has been written by Theodore Ts'o <tytso@mit.edu>.
425 option but currently ignores it because the second
426 extended file system does not support fragments yet.
428 There may be other ones. Please, report them to the author.
431 is part of the e2fsprogs package and is available from
432 http://e2fsprogs.sourceforge.net.