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 file systems.
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 "creator operating system" for the
123 file system unless it is overriden on the command line.
124 The default value is the OS for which the
126 executable was compiled.
129 This relation specifies the default file system type if the user does not
134 is not started using a program name of the form
135 .BI mkfs. fs-type\fR.
136 If both the user and the
138 file do not specify a default file system type, mke2fs will use a
139 default file system type of
141 if a journal was requested via a command-line option, or
146 This relation specifies the directory where the undo file should be
147 stored. It can be overridden via the
148 .B E2FSPROGS_UNDO_DIR
149 environment variable. If the directory location is set to the value
152 will not create an undo file.
154 In addition, any tags that can be specified in a per-file system tags
155 subsection as defined below (e.g.,
161 etc.) can also be specified in the
163 stanza to specify the default value to be used if the user does not
164 specify one on the command line, and the file system-type
165 specific section of the configuration file does not specify a default value.
166 .SH THE [fs_types] STANZA
169 stanza names a file system type or usage type which can be specified via the
179 program constructs a list of fs_types by concatenating the file system
180 type (i.e., ext2, ext3, etc.) with the usage type list. For most
181 configuration options,
183 will look for a subsection in the
185 stanza corresponding with each entry in the constructed list, with later
186 entries overriding earlier file system or usage types.
188 example, consider the following
194 base_features = sparse_super,filetype,resize_inode,dir_index
208 features = has_journal
214 features = extents,flex_bg
230 features = ^resize_inode
238 If mke2fs started with a program name of
240 then the file system type of ext4 will be used. If the file system is
241 smaller than 3 megabytes, and no usage type is specified, then
246 This results in an fs_types list of "ext4, floppy". Both the ext4
247 subsection and the floppy subsection define an
249 relation, but since the later entries in the fs_types list supersede
250 earlier ones, the configuration parameter for fs_types.floppy.inode_size
251 will be used, so the file system will have an inode size of 128.
253 The exception to this resolution is the
255 tag, which specifies a set of changes to the features used by the
256 file system, and which is cumulative. So in the above example, first
257 the configuration relation defaults.base_features would enable an
258 initial feature set with the sparse_super, filetype, resize_inode, and
259 dir_index features enabled. Then configuration relation
260 fs_types.ext4.features would enable the extents and flex_bg
261 features, and finally the configuration relation
262 fs_types.floppy.features would remove
263 the resize_inode feature, resulting in a file system feature set
264 consisting of the sparse_super, filetype, dir_index,
265 extents_and flex_bg features.
267 For each file system type, the following tags may be used in that
268 fs_type's subsection. These tags may also be used in the
273 This relation specifies the features which are initially enabled for this
274 file system type. Only one
276 will be used, so if there are multiple entries in the fs_types list
277 whose subsections define the
279 relation, only the last will be used by
282 .I enable_periodic_fsck
283 This boolean relation specifies whether periodic file system checks should be
284 enforced at boot time. If set to true, checks will be forced every
285 180 days, or after a random number of mounts. These values may
286 be changed later via the
290 command-line options to
294 Change the behavior of the kernel code when errors are detected.
295 In all cases, a file system error will cause
297 to check the file system on the next boot.
299 can be one of the following:
303 Continue normal execution.
306 Remount file system read-only.
309 Cause a kernel panic.
313 This relation specifies a comma-separated list of features edit
314 requests which modify the feature set
315 used by the newly constructed file system. The syntax is the same as the
317 command-line option to
319 that is, a feature can be prefixed by a caret ('^') symbol to disable
320 a named feature. Each
322 relation specified in the fs_types list will be applied in the order
323 found in the fs_types list.
326 This boolean relation, if set to a value of true, forces
328 to always try to create an undo file, even if the undo file might be
329 huge and it might extend the time to create the file system image
330 because the inode table isn't being initialized lazily.
333 This relation specifies set of features which should be enabled or
334 disabled after applying the features listed in the
338 relations. It may be overridden by the
340 command-line option to
343 .I auto_64-bit_support
344 This relation is a boolean which specifies whether
346 should automatically add the 64bit feature if the number of blocks for
347 the file system requires this feature to be enabled. The resize_inode
348 feature is also automatically disabled since it doesn't support 64-bit
352 This relation specifies the set of mount options which should be enabled
353 by default. These may be changed at a later time with the
355 command-line option to
359 This relation specifies the default blocksize if the user does not
360 specify a blocksize on the command line.
363 This boolean relation specifies whether the inode table should
364 be lazily initialized. It only has meaning if the uninit_bg feature is
365 enabled. If lazy_itable_init is true and the uninit_bg feature is
366 enabled, the inode table will
367 not be fully initialized by
369 This speeds up file system
370 initialization noticeably, but it requires the kernel to finish
371 initializing the file system in the background when the file system is
375 This boolean relation specifies whether the journal inode should be
376 lazily initialized. It only has meaning if the has_journal feature is
377 enabled. If lazy_journal_init is true, the journal inode will not be
380 This speeds up file system initialization noticeably, but carries some
381 small risk if the system crashes before the journal has been overwritten
385 This relation specifies the location of the journal.
388 This relation indicates whether file systems with the
390 feature enabled should be created with 0, 1, or 2 backup superblocks.
392 .I packed_meta_blocks
393 This boolean relation specifies whether the allocation bitmaps, inode
394 table, and journal should be located at the beginning of the file system.
397 This relation specifies the default inode ratio if the user does not
398 specify one on the command line.
401 This relation specifies the default inode size if the user does not
402 specify one on the command line.
405 This relation specifies the default percentage of file system blocks
406 reserved for the super-user, if the user does not specify one on the command
410 This relation specifies the default hash algorithm used for the
411 new file systems with hashed b-tree directories. Valid algorithms
419 This relation specifies the number of block groups that will be packed
420 together to create one large virtual block group on an ext4 file system.
421 This improves meta-data locality and performance on meta-data heavy
422 workloads. The number of groups must be a power of 2 and may only be
423 specified if the flex_bg file system feature is enabled.
426 This relation specifies additional extended options which should be
429 as if they were prepended to the argument of the
431 option. This can be used to configure the default extended options used
434 on a per-file system type basis.
437 This boolean relation specifies whether the
439 should attempt to discard device prior to file system creation.
442 This relation specifies the default cluster size if the bigalloc file
443 system feature is enabled. It can be overridden via the
445 command line option to
449 This boolean relation enables the creation of pre-allocated files as
450 part of formatting the file system. The extent tree blocks for these
451 pre-allocated files will be placed near the beginning of the file
452 system, so that if all of the other metadata blocks are also configured
453 to be placed near the beginning of the file system (by disabling the
454 backup superblocks, using the packed_meta_blocks option, etc.), the data
455 blocks of the pre-allocated files will be contiguous.
458 This relation specifies the directory where huge files are created,
459 relative to the file system root.
462 This relation controls the user ownership for all of the files and
463 directories created by the
468 This relation controls the group ownership for all of the files and
469 directories created by the
474 This relation specifies the umask used when creating the files and
480 This relation specifies the number of huge files to be created. If this
481 relation is not specified, or is set to zero, and the
483 relation is non-zero, then
485 will create as many huge files as can fit to fill the entire file system.
488 This relation specifies how much space should be reserved for other
492 This relation specifies the size of the huge files. If this relation is
493 not specified, the default is to fill the entire file system.
496 This relation specifies the alignment for the start block of the huge
497 files. It also forces the size of huge files to be a multiple of the
498 requested alignment. If this relation is not specified, no alignment
499 requirement will be imposed on the huge files.
501 .I hugefiles_align_disk
502 This relations specifies whether the alignment should be relative to the
503 beginning of the hard drive (assuming that the starting offset of the
504 partition is available to mke2fs). The default value is false, which
505 will cause hugefile alignment to be relative to the beginning of the
509 This relation specifies the base file name for the huge files.
512 This relation specifies the (zero-padded) width of the field for the
516 This boolean relation specifies wheather mke2fs will issue a warning
517 when creating a file system with 128 byte inodes (and so therefore will
518 not support dates after January 19th, 2038). The default value is true,
519 except for file systems created for the GNU Hurd since it only supports
523 This boolean relation specifies whether or not zero blocks will be
524 written to the hugefiles while
526 is creating them. By default, zero blocks will be written to the huge
527 files to avoid stale data from being made available to potentially
528 untrusted user programs, unless the device supports a discard/trim
529 operation which will take care of zeroing the device blocks. By setting
531 to false, this step will always be skipped, which can be useful if it is
532 known that the disk has been previously erased, or if the user programs
533 that will have access to the huge files are trusted to not reveal stale
537 This relation defines the file name encoding to be used if the casefold
538 feature is enabled. Currently the only valid encoding is utf8-12.1 or
539 utf8, which requests the most recent Unicode version; since 12.1 is the only
540 available Unicode version, utf8 and utf8-12.1 have the same result.
542 This relation defines encoding-specific flags. For utf8 encodings, the
543 only available flag is strict, which will cause attempts to create file
544 names containing invalid Unicode characters to be rejected by the
545 kernel. Strict mode is not enabled by default.
546 .SH THE [devices] STANZA
549 stanza names device name so that per-device defaults can be specified.
552 This relation specifies the default parameter for the
554 option, if this option isn't specified on the command line.
557 This relation specifies the default parameter for the
559 option, if this option isn't specified on the command line.
563 The configuration file for