2 .\" Copyright 2006 by Theodore Ts'o. All Rights Reserved.
3 .\" This file may be copied under the terms of the GNU Public License.
5 .TH mke2fs.conf 5 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
7 mke2fs.conf \- Configuration file for mke2fs
10 is the configuration file for
12 It controls the default parameters used by
14 when it is creating ext2, ext3, or ext4 filesystems.
18 file uses an INI-style format. Stanzas, or top-level sections, are
19 delimited by square braces: [ ]. Within each section, each line
20 defines a relation, which assigns tags to values, or to a subsection,
21 which contains further relations or subsections.
22 .\" Tags can be assigned multiple values
23 An example of the INI-style format used by this configuration file
38 subtag1 = subtag_value_a
40 subtag1 = subtag_value_b
42 subtag2 = subtag_value_c
52 Comments are delimited by a semicolon (';') or a hash ('#') character
53 at the beginning of the comment, and are terminated by the end of
56 Tags and values must be quoted using double quotes if they contain
57 spaces. Within a quoted string, the standard backslash interpretations
58 apply: "\en" (for the newline character),
59 "\et" (for the tab character), "\eb" (for the backspace character),
60 and "\e\e" (for the backslash character).
62 Some relations expect a boolean value. The parser is quite liberal on
63 recognizing ``yes'', '`y'', ``true'', ``t'', ``1'', ``on'', etc. as a
64 boolean true value, and ``no'', ``n'', ``false'', ``nil'', ``0'',
65 ``off'' as a boolean false value.
67 The following stanzas are used in the
69 file. They will be described in more detail in future sections of this
73 Contains relations which influence how mke2fs behaves.
76 Contains relations which define the default parameters
79 In general, these defaults may be overridden by a definition in the
81 stanza, or by a command-line option provided by the user.
84 Contains relations which define defaults that should be used for specific
85 file system and usage types. The file system type and usage type can be
86 specified explicitly using
94 Contains relations which define defaults for specific devices.
95 .SH THE [options] STANZA
96 The following relations are defined in the
101 If this relation is set to a positive integer, then mke2fs will
104 seconds after asking the user for permission to proceed and
105 then continue, even if the
106 user has not answered the question. Defaults to 0, which means to wait
107 until the user answers the question one way or another.
110 If this relation is set to a positive integer, then while writing the
111 inode table, mke2fs will request the operating system flush out pending
112 writes to initialize the inode table every
114 block groups. This is needed to work around buggy kernels that don't
115 handle writeback throttling correctly.
116 .SH THE [defaults] STANZA
117 The following relations are defined in the
122 This relation specifies the default filesystem type if the user does not
127 is not started using a program name of the form
128 .BI mkfs. fs-type\fR.
129 If both the user and the
131 file do not specify a default filesystem type, mke2fs will use a
132 default filesystem type of
134 if a journal was requested via a command-line option, or
139 This relation specifies the directory where the undo file should be
140 stored. It can be overridden via the
141 .B E2FSPROGS_UNDO_DIR
142 environment variable. If the directory location is set to the value
145 will not create an undo file.
147 In addition, any tags that can be specified in a per-file system tags
148 subsection as defined below (e.g.,
154 etc.) can also be specified in the
156 stanza to specify the default value to be used if the user does not
157 specify one on the command line, and the filesystem-type
158 specific section of the configuration file does not specify a default value.
159 .SH THE [fs_types] STANZA
162 stanza names a filesystem type or usage type which can be specified via the
172 program constructs a list of fs_types by concatenating the filesystem
173 type (i.e., ext2, ext3, etc.) with the usage type list. For most
174 configuration options,
176 will look for a subsection in the
178 stanza corresponding with each entry in the constructed list, with later
179 entries overriding earlier filesystem or usage types.
181 example, consider the following
187 base_features = sparse_super,filetype,resize_inode,dir_index
201 features = has_journal
207 features = extents,flex_bg
223 features = ^resize_inode
231 If mke2fs started with a program name of
233 then the filesystem type of ext4 will be used. If the filesystem is
234 smaller than 3 megabytes, and no usage type is specified, then
239 This results in an fs_types list of "ext4, floppy". Both the ext4
240 subsection and the floppy subsection define an
242 relation, but since the later entries in the fs_types list supersede
243 earlier ones, the configuration parameter for fs_types.floppy.inode_size
244 will be used, so the filesystem will have an inode size of 128.
246 The exception to this resolution is the
248 tag, which specifies a set of changes to the features used by the
249 filesystem, and which is cumulative. So in the above example, first
250 the configuration relation defaults.base_features would enable an
251 initial feature set with the sparse_super, filetype, resize_inode, and
252 dir_index features enabled. Then configuration relation
253 fs_types.ext4.features would enable the extents and flex_bg
254 features, and finally the configuration relation
255 fs_types.floppy.features would remove
256 the resize_inode feature, resulting in a filesystem feature set
257 consisting of the sparse_super, filetype, dir_index,
258 extents_and flex_bg features.
260 For each filesystem type, the following tags may be used in that
261 fs_type's subsection. These tags may also be used in the
266 This relation specifies the features which are initially enabled for this
267 filesystem type. Only one
269 will be used, so if there are multiple entries in the fs_types list
270 whose subsections define the
272 relation, only the last will be used by
275 .I enable_periodic_fsck
276 This boolean relation specifies whether periodic filesystem checks should be
277 enforced at boot time. If set to true, checks will be forced every
278 180 days, or after a random number of mounts. These values may
279 be changed later via the
283 command-line options to
287 Change the behavior of the kernel code when errors are detected.
288 In all cases, a filesystem error will cause
290 to check the filesystem on the next boot.
292 can be one of the following:
296 Continue normal execution.
299 Remount filesystem read-only.
302 Cause a kernel panic.
306 This relation specifies a comma-separated list of features edit
307 requests which modify the feature set
308 used by the newly constructed filesystem. The syntax is the same as the
310 command-line option to
312 that is, a feature can be prefixed by a caret ('^') symbol to disable
313 a named feature. Each
315 relation specified in the fs_types list will be applied in the order
316 found in the fs_types list.
319 This boolean relation, if set to a value of true, forces
321 to always try to create an undo file, even if the undo file might be
322 huge and it might extend the time to create the filesystem image
323 because the inode table isn't being initialized lazily.
326 This relation specifies set of features which should be enabled or
327 disabled after applying the features listed in the
331 relations. It may be overridden by the
333 command-line option to
336 .I auto_64-bit_support
337 This relation is a boolean which specifies whether
339 should automatically add the 64bit feature if the number of blocks for
340 the file system requires this feature to be enabled. The resize_inode
341 feature is also automatically disabled since it doesn't support 64-bit
345 This relation specifies the set of mount options which should be enabled
346 by default. These may be changed at a later time with the
348 command-line option to
352 This relation specifies the default blocksize if the user does not
353 specify a blocksize on the command line.
356 This boolean relation specifies whether the inode table should
357 be lazily initialized. It only has meaning if the uninit_bg feature is
358 enabled. If lazy_itable_init is true and the uninit_bg feature is
359 enabled, the inode table will
360 not be fully initialized by
362 This speeds up filesystem
363 initialization noticeably, but it requires the kernel to finish
364 initializing the filesystem in the background when the filesystem is
368 This boolean relation specifies whether the journal inode should be
369 lazily initialized. It only has meaning if the has_journal feature is
370 enabled. If lazy_journal_init is true, the journal inode will not be
373 This speeds up filesystem initialization noticeably, but carries some
374 small risk if the system crashes before the journal has been overwritten
378 This relation specifies the location of the journal.
381 This relation indicates whether file systems with the
383 feature enabled should be created with 0, 1, or 2 backup superblocks.
385 .I packed_meta_blocks
386 This boolean relation specifies whether the allocation bitmaps, inode
387 table, and journal should be located at the beginning of the file system.
390 This relation specifies the default inode ratio if the user does not
391 specify one on the command line.
394 This relation specifies the default inode size if the user does not
395 specify one on the command line.
398 This relation specifies the default percentage of filesystem blocks
399 reserved for the super-user, if the user does not specify one on the command
403 This relation specifies the default hash algorithm used for the
404 new filesystems with hashed b-tree directories. Valid algorithms
412 This relation specifies the number of block groups that will be packed
413 together to create one large virtual block group on an ext4 filesystem.
414 This improves meta-data locality and performance on meta-data heavy
415 workloads. The number of groups must be a power of 2 and may only be
416 specified if the flex_bg filesystem feature is enabled.
419 This relation specifies additional extended options which should be
422 as if they were prepended to the argument of the
424 option. This can be used to configure the default extended options used
427 on a per-filesystem type basis.
430 This boolean relation specifies whether the
432 should attempt to discard device prior to filesystem creation.
435 This relation specifies the default cluster size if the bigalloc file
436 system feature is enabled. It can be overridden via the
438 command line option to
442 This boolean relation enables the creation of pre-allocated files as
443 part of formatting the file system. The extent tree blocks for these
444 pre-allocated files will be placed near the beginning of the file
445 system, so that if all of the other metadata blocks are also configured
446 to be placed near the beginning of the file system (by disabling the
447 backup superblocks, using the packed_meta_blocks option, etc.), the data
448 blocks of the pre-allocated files will be contiguous.
451 This relation specifies the directory where huge files are created,
452 relative to the filesystem root.
455 This relation controls the user ownership for all of the files and
456 directories created by the
461 This relation controls the group ownership for all of the files and
462 directories created by the
467 This relation specifies the umask used when creating the files and
473 This relation specifies the number of huge files to be created. If this
474 relation is not specified, or is set to zero, and the
476 relation is non-zero, then
478 will create as many huge files as can fit to fill the entire file system.
481 This relation specifies how much space should be reserved for other
485 This relation specifies the size of the huge files. If this relation is
486 not specified, the default is to fill the entire file system.
489 This relation specifies the alignment for the start block of the huge
490 files. It also forces the size of huge files to be a multiple of the
491 requested alignment. If this relation is not specified, no alignment
492 requirement will be imposed on the huge files.
494 .I hugefiles_align_disk
495 This relations specifies whether the alignment should be relative to the
496 beginning of the hard drive (assuming that the starting offset of the
497 partition is available to mke2fs). The default value is false, which
498 will cause hugefile alignment to be relative to the beginning of the
502 This relation specifies the base file name for the huge files.
505 This relation specifies the (zero-padded) width of the field for the
509 This boolean relation specifies whether or not zero blocks will be
510 written to the hugefiles while
512 is creating them. By default, zero blocks will be written to the huge
513 files to avoid stale data from being made available to potentially
514 untrusted user programs, unless the device supports a discard/trim
515 operation which will take care of zeroing the device blocks. By setting
517 to false, this step will always be skipped, which can be useful if it is
518 known that the disk has been previously erased, or if the user programs
519 that will have access to the huge files are trusted to not reveal stale
523 This relation defines the file name encoding to be used if the casefold
524 feature is enabled. Currently the only valid encoding is utf8-12.1 or
525 utf8, which requests the most recent Unicode version; since 12.1 is the only
526 available Unicode version, utf8 and utf8-12.1 have the same result.
528 This relation defines encoding-specific flags. For utf8 encodings, the
529 only available flag is strict, which will cause attempts to create file
530 names containing invalid Unicode characters to be rejected by the
531 kernel. Strict mode is not enabled by default.
532 .SH THE [devices] STANZA
535 stanza names device name so that per-device defaults can be specified.
538 This relation specifies the default parameter for the
540 option, if this option isn't specified on the command line.
543 This relation specifies the default parameter for the
545 option, if this option isn't specified on the command line.
549 The configuration file for