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 an command-line option provided by the user.
84 Contains relations which define defaults that should be used for specific
85 filesystem types. The filesystem type can be specified explicitly using
90 .SH THE [options] STANZA
91 The following relations are defined in the
96 If this relation is set to a positive integer, then if mke2fs will
99 seconds, after asking the user for permission to proceed, even if the
100 user has not answered the question. Defaults to 0, which means to wait
101 until the user answers the question one way or another.
102 .SH THE [defaults] STANZA
103 The following relations are defined in the
108 This relation specifies the filesystems features which are enabled in
109 newly created filesystems. It may be overridden by the
111 relation found in the filesystem or usage type subsection of
117 This relation specifies a set of features that should be added or
118 removed to the features listed in the
120 relation. It may be overridden by the filesystem-specific
122 in the filesystem or usage type subsection of
130 .I enable_periodic_fsck
131 This boolean relation specifies whether periodic filesystem checks should be
132 enforced at boot time. If set to true, checks will be forced every
133 180 days, or after a random number of mounts. These values may
134 be changed later via the
138 command-line options to
142 This boolean relation, if set to a value of true, forces
144 to always try to create an undo file, even if the undo file might be
145 huge and it might extend the time to create the filesystem image
146 because the inode table isn't being initialized lazily.
149 This relation specifies the default filesystem type if the user does not
154 is not started using a program name of the form
155 .BI mkfs. fs-type\fR.
156 If both the user and the
158 file does not specify a default filesystem type, mke2fs will use a
159 default filesystem type of
161 if a journal was requested via a command-line option, or
166 This relation specifies the default blocksize if the user does not
167 specify a blocksize on the command line, and the filesystem-type
168 specific section of the configuration file does not specify a blocksize.
171 This relation specifies the default hash algorithm used for the
172 new filesystems with hashed b-tree directories. Valid algorithms
180 This relation specifies the default inode ratio if the user does not
181 specify one on the command line, and the filesystem-type
182 specific section of the configuration file does not specify a default
186 This relation specifies the default inode size if the user does not
187 specify one on the command line, and the filesystem-type
188 specific section of the configuration file does not specify a default
192 This relation specifies the default percentage of filesystem blocks
193 reserved for the super-user, if the user does not
194 specify one on the command line, and the filesystem-type
195 specific section of the configuration file does not specify a default
196 reserved ratio. This value can be a floating point number.
199 This relation specifies the directory where the undo file should be
200 stored. It can be overridden via the
201 .B E2FSPROGS_UNDO_DIR
202 environment variable. If the directory location is set to the value
205 will not create an undo file.
206 .SH THE [fs_types] STANZA
209 stanza names a filesystem type or usage type which can be specified via the
219 program constructs a list of fs_types by concatenating the filesystem
220 type (i.e., ext2, ext3, etc.) with the usage type list. For most
221 configuration options,
223 will look for a subsection in the
225 stanza corresponding with each entry in the constructed list, with later
226 entries overriding earlier filesystem or usage types.
228 example, consider the following
234 base_features = sparse_super,filetype,resize_inode,dir_index
248 features = has_journal
254 features = extents,flex_bg
270 features = ^resize_inode
278 If mke2fs started with a program name of
280 then the filesystem type of ext4 will be used. If the filesystem is
281 smaller than 3 megabytes, and no usage type is specified, then
286 This results in an fs_types list of "ext4, floppy". Both the ext4
287 subsection and the floppy subsection define an
289 relation, but since the later entries in the fs_types list supersede
290 earlier ones, the configuration parameter for fs_types.floppy.inode_size
291 will be used, so the filesystem will have an inode size of 128.
293 The exception to this resolution is the
295 tag, which is specifies a set of changes to the features used by the
296 filesystem, and which is cumulative. So in the above example, first
297 the configuration relation defaults.base_features would enable an
298 initial feature set with the sparse_super, filetype, resize_inode, and
299 dir_index features enabled. Then configuration relation
300 fs_types.ext4.features would enable the extents and flex_bg
301 features, and finally the configuration relation
302 fs_types.floppy.features would remove
303 the resize_inode feature, resulting in a filesystem feature set
304 consisting of the sparse_super, filetype, resize_inode, dir_index,
305 extents_and flex_bg features.
307 For each filesystem type, the following tags may be used in that
308 fs_type's subsection:
311 This relation specifies the features which are initially enabled for this
312 filesystem type. Only one
314 will be used, so if there are multiple entries in the fs_types list
315 whose subsections define the
317 relation, only the last will be used by
321 This relation specifies a comma-separated list of features edit
322 requests which modify the feature set
323 used by the newly constructed filesystem. The syntax is the same as the
325 command-line option to
327 that is, a feature can be prefixed by a caret ('^') symbol to disable
328 a named feature. Each
330 relation specified in the fs_types list will be applied in the order
331 found in the fs_types list.
334 This relation specifies set of features which should be enabled or
335 disabled after applying the features listed in the
339 relations. It may be overridden by the
341 command-line option to
344 .I auto_64-bit_support
345 This relation is a boolean which specifies whether
347 should automatically add the 64bit feature if the number of blocks for
348 the file system requires this feature to be enabled. The resize_inode
349 feature is also automatically disabled since it doesn't support 64-bit
353 This relation specifies the set of mount options which should be enabled
354 by default. These may be changed at a later time with the
356 command-line option to
360 This relation specifies the default blocksize if the user does not
361 specify a blocksize on the command line.
364 This boolean relation specifies whether the inode table should
365 be lazily initialized. It only has meaning if the uninit_bg feature is
366 enabled. If lazy_itable_init is true and the uninit_bg feature is
367 enabled, the inode table will
368 not fully initialized by
370 This speeds up filesystem
371 initialization noticeably, but it requires the kernel to finish
372 initializing the filesystem in the background when the filesystem is
376 This relation specifies the location of the journal.
379 This relation indicates whether file systems with the
381 feature enabled should be created with 0, 1, or 2 backup superblocks.
383 .I packed_meta_blocks
384 This boolean relation specifes whether the allocation bitmaps, inode
385 table, and journal should be located at the beginning of the file system.
388 This relation specifies the default inode ratio if the user does not
389 specify one on the command line.
392 This relation specifies the default inode size if the user does not
393 specify one on the command line.
396 This relation specifies the default percentage of filesystem blocks
397 reserved for the super-user, if the user does not specify one on the command
401 This relation specifies the default hash algorithm used for the
402 new filesystems with hashed b-tree directories. Valid algorithms
410 This relation specifies the number of block groups that will be packed
411 together to create one large virtual block group on an ext4 filesystem.
412 This improves meta-data locality and performance on meta-data heavy
413 workloads. The number of groups must be a power of 2 and may only be
414 specified if the flex_bg filesystem feature is enabled.
417 This relation specifies additional extended options which should be
420 as if they were prepended to the argument of the
422 option. This can be used to configure the default extended options used
425 on a per-filesystem type basis.
428 This boolean relation specifies whether the
430 should attempt to discard device prior to filesystem creation.
433 This relation specifies the default cluster size if the bigalloc file
434 system feature is enabled. It can be overridden via the
436 command line option to
440 This boolean relation enables the creation of pre-allocated files as
441 part of formatting the file system.
444 This relation controls the user ownership for all of the files and
445 directories created by the
450 This relation controls the group ownership for all of the files and
451 directories created by the
456 This relation specifies the umask used when creating the files and
462 This relation specifies the number of huge files to be created. If this
463 relation is not specified, or is set to zero, and the
465 relation is non-zero, then
467 will create as many huge files as can fit to fill the entire file system.
470 This relation specifies how much space should be reserved for other
474 This relation specifies the size of the huge files. If this relation is
475 not specified, the default is to fill the entire file system.
478 This relation specifies the alignment for the start block of the huge
479 files. It also forces the size of huge files to be a multiple of the
480 requested alignment. If this relation is not specified, no alignment
481 requirement will be imposed on the huge files.
483 .I hugefiles_align_disk
484 Thie relations specifies whether the alignment should be relative to the
485 beginning of the hard drive (assuming that the starting offset of the
486 partition is available to mke2fs). The default value is false, which
487 if will cause hugefile alignment to be relative to the beginning of the
491 This relation specifies the base file name for the huge files.
494 This relation specifies the (zero-padded) width of the field for the
498 This boolean relation specifies whether or not zero blocks will be
499 written to the hugefiles while
501 is creating them. By default, zero blocks will be written to the huge
502 files to avoid stale data from being made available to potentially
503 untrusted user programs, unless the device supports a discard/trim
504 operation which will take care of zeroing the device blocks. By
506 to false, this step will always be skipped, which can be useful if it is
507 known that the disk has been previously erased, or if the user programs
508 that will have access to the huge files are trusted to not reveal stale
510 .SH THE [devices] STANZA
513 stanza names device name so that per-device defaults can be specified.
516 This relation specifies the default parameter for the
518 option, if this option isn't specified on the command line.
521 This relation specifies the default parameter for the
523 option, if this option isn't specified on the command line.
527 The configuration file for