misc/mke2fs.conf.5.in

   1 .\" -*- nroff -*-
   2 .\" Copyright 2006 by Theodore Ts'o.  All Rights Reserved.
   3 .\" This file may be copied under the terms of the GNU Public License.
   4 .\"
   5 .TH mke2fs.conf 5 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
   6 .SH NAME
   7 mke2fs.conf \- Configuration file for mke2fs
   8 .SH DESCRIPTION
   9 .I mke2fs.conf
  10 is the configuration file for
  11 .BR mke2fs (8).
  12 It controls the default parameters used by
  13 .BR mke2fs (8)
  14 when it is creating ext2, ext3, or ext4 filesystems.
  15 .PP
  16 The
  17 .I mke2fs.conf
  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
  24 follows below:
  25 .P
  26         [section1]
  27 .br
  28                 tag1 = value_a
  29 .br
  30                 tag1 = value_b
  31 .br
  32                 tag2 = value_c
  33 .P
  34         [section 2]
  35 .br
  36                 tag3 = {
  37 .br
  38                         subtag1 = subtag_value_a
  39 .br
  40                         subtag1 = subtag_value_b
  41 .br
  42                         subtag2 = subtag_value_c
  43 .br
  44                 }
  45 .br
  46                 tag1 = value_d
  47 .br
  48                 tag2 = value_e
  49 .br
  50         }
  51 .P
  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
  54 line character.
  55 .P
  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).
  61 .P
  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.
  66 .P
  67 The following stanzas are used in the
  68 .I mke2fs.conf
  69 file.  They will be described in more detail in future sections of this
  70 document.
  71 .TP
  72 .I [options]
  73 Contains relations which influence how mke2fs behaves.
  74 .TP
  75 .I [defaults]
  76 Contains relations which define the default parameters
  77 used by
  78 .BR mke2fs (8).
  79 In general, these defaults may be overridden by a definition in the
  80 .B fs_types
  81 stanza, or by a command-line option provided by the user.
  82 .TP
  83 .I [fs_types]
  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
  87 the
  88 .BR \-t and \-T
  89 options to
  90 .BR mke2fs (8),
  91 respectively.
  92 .TP
  93 .I [devices]
  94 Contains relations which define defaults for specific devices.
  95 .SH THE [options] STANZA
  96 The following relations are defined in the
  97 .I [options]
  98 stanza.
  99 .TP
 100 .I proceed_delay
 101 If this relation is set to a positive integer, then if mke2fs will
 102 proceed after waiting
 103 .I proceed_delay
 104 seconds, after asking the user for permission to proceed, even if the
 105 user has not answered the question.  Defaults to 0, which means to wait
 106 until the user answers the question one way or another.
 107 .SH THE [defaults] STANZA
 108 The following relations are defined in the
 109 .I [defaults]
 110 stanza.
 111 .TP
 112 .I fs_type
 113 This relation specifies the default filesystem type if the user does not
 114 specify it via the
 115 .B \-t
 116 option, or if
 117 .B mke2fs
 118 is not started using a program name of the form
 119 .BI mkfs. fs-type\fR.
 120 If both the user and the
 121 .B mke2fs.conf
 122 file do not specify a default filesystem type, mke2fs will use a
 123 default filesystem type of
 124 .IR ext3
 125 if a journal was requested via a command-line option, or
 126 .I ext2
 127 if not.
 128 .TP
 129 .I undo_dir
 130 This relation specifies the directory where the undo file should be
 131 stored.  It can be overridden via the
 132 .B E2FSPROGS_UNDO_DIR
 133 environment variable.  If the directory location is set to the value
 134 .IR none ,
 135 .B mke2fs
 136 will not create an undo file.
 137 .PP
 138 In addition, any tags that can be specified in a per-file system tags
 139 subsection as defined below (e.g.,
 140 .IR blocksize ,
 141 .IR hash_alg ,
 142 .IR inode_ratio ,
 143 .IR inode_size ,
 144 .IR reserved_ratio ,
 145 etc.) can also be specified in the
 146 .I defaults
 147 stanza to specify the default value to be used if the user does not
 148 specify one on the command line, and the filesystem-type
 149 specific section of the configuration file does not specify a default value.
 150 .SH THE [fs_types] STANZA
 151 Each tag in the
 152 .I [fs_types]
 153 stanza names a filesystem type or usage type which can be specified via the
 154 .B \-t
 155 or
 156 .B \-T
 157 options to
 158 .BR mke2fs (8),
 159 respectively.
 160 .P
 161 The
 162 .B mke2fs
 163 program constructs a list of fs_types by concatenating the filesystem
 164 type (i.e., ext2, ext3, etc.) with the usage type list.  For most
 165 configuration options,
 166 .B mke2fs
 167 will look for a subsection in the
 168 .I [fs_types]
 169 stanza corresponding with each entry in the constructed list, with later
 170 entries overriding earlier filesystem or usage types.
 171 For
 172 example, consider the following
 173 .B mke2fs.conf
 174 fragment:
 175 .P
 176 [defaults]
 177 .br
 178         base_features = sparse_super,filetype,resize_inode,dir_index
 179 .br
 180         blocksize = 4096
 181 .br
 182         inode_size = 256
 183 .br
 184         inode_ratio = 16384
 185 .br
 186
 187 .br
 188 [fs_types]
 189 .br
 190         ext3 = {
 191 .br
 192                 features = has_journal
 193 .br
 194         }
 195 .br
 196         ext4 = {
 197 .br
 198                 features = extents,flex_bg
 199 .br
 200                 inode_size = 256
 201 .br
 202         }
 203 .br
 204         small = {
 205 .br
 206                 blocksize = 1024
 207 .br
 208                 inode_ratio = 4096
 209 .br
 210         }
 211 .br
 212         floppy = {
 213 .br
 214                 features = ^resize_inode
 215 .br
 216                 blocksize = 1024
 217 .br
 218                 inode_size = 128
 219 .br
 220         }
 221 .P
 222 If mke2fs started with a program name of
 223 .BR mke2fs.ext4 ,
 224 then the filesystem type of ext4 will be used.  If the filesystem is
 225 smaller than 3 megabytes, and no usage type is specified, then
 226 .B mke2fs
 227 will use a default
 228 usage type of
 229 .IR floppy .
 230 This results in an fs_types list of "ext4, floppy".   Both the ext4
 231 subsection and the floppy subsection define an
 232 .I inode_size
 233 relation, but since the later entries in the fs_types list supersede
 234 earlier ones, the configuration parameter for fs_types.floppy.inode_size
 235 will be used, so the filesystem  will have an inode size of 128.
 236 .P
 237 The exception to this resolution is the
 238 .I features
 239 tag, which specifies a set of changes to the features used by the
 240 filesystem, and which is cumulative.  So in the above example, first
 241 the configuration relation defaults.base_features would enable an
 242 initial feature set with the sparse_super, filetype, resize_inode, and
 243 dir_index features enabled.  Then configuration relation
 244 fs_types.ext4.features would enable the extents and flex_bg
 245 features, and finally the configuration relation
 246 fs_types.floppy.features would remove
 247 the resize_inode feature, resulting in a filesystem feature set
 248 consisting of the sparse_super, filetype, dir_index,
 249 extents_and flex_bg features.
 250 .P
 251 For each filesystem type, the following tags may be used in that
 252 fs_type's subsection.   These tags may also be used in the
 253 .I default
 254 section:
 255 .TP
 256 .I base_features
 257 This relation specifies the features which are initially enabled for this
 258 filesystem type.  Only one
 259 .I base_features
 260 will be used, so if there are multiple entries in the fs_types list
 261 whose subsections define the
 262 .I base_features
 263 relation, only the last will be used by
 264 .BR mke2fs (8).
 265 .TP
 266 .I enable_periodic_fsck
 267 This boolean relation specifies whether periodic filesystem checks should be
 268 enforced at boot time.  If set to true, checks will be forced every
 269 180 days, or after a random number of mounts.  These values may
 270 be changed later via the
 271 .B -i
 272 and
 273 .B -c
 274 command-line options to
 275 .BR tune2fs (8).
 276 .TP
 277 .I errors
 278 Change the behavior of the kernel code when errors are detected.
 279 In all cases, a filesystem error will cause
 280 .BR e2fsck (8)
 281 to check the filesystem on the next boot.
 282 .I errors
 283 can be one of the following:
 284 .RS 1.2i
 285 .TP 1.2i
 286 .B continue
 287 Continue normal execution.
 288 .TP
 289 .B remount-ro
 290 Remount filesystem read-only.
 291 .TP
 292 .B panic
 293 Cause a kernel panic.
 294 .RE
 295 .TP
 296 .I features
 297 This relation specifies a comma-separated list of features edit
 298 requests which modify the feature set
 299 used by the newly constructed filesystem.  The syntax is the same as the
 300 .B -O
 301 command-line option to
 302 .BR mke2fs (8);
 303 that is, a feature can be prefixed by a caret ('^') symbol to disable
 304 a named feature.  Each
 305 .I feature
 306 relation specified in the fs_types list will be applied in the order
 307 found in the fs_types list.
 308 .TP
 309 .I force_undo
 310 This boolean relation, if set to a value of true, forces
 311 .B mke2fs
 312 to always try to create an undo file, even if the undo file might be
 313 huge and it might extend the time to create the filesystem image
 314 because the inode table isn't being initialized lazily.
 315 .TP
 316 .I default_features
 317 This relation specifies set of features which should be enabled or
 318 disabled after applying the features listed in the
 319 .I base_features
 320 and
 321 .I features
 322 relations.  It may be overridden by the
 323 .B -O
 324 command-line option to
 325 .BR mke2fs (8).
 326 .TP
 327 .I auto_64-bit_support
 328 This relation is a boolean which specifies whether
 329 .BR mke2fs (8)
 330 should automatically add the 64bit feature if the number of blocks for
 331 the file system requires this feature to be enabled.  The resize_inode
 332 feature is also automatically disabled since it doesn't support 64-bit
 333 block numbers.
 334 .TP
 335 .I default_mntopts
 336 This relation specifies the set of mount options which should be enabled
 337 by default.  These may be changed at a later time with the
 338 .B -o
 339 command-line option to
 340 .BR tune2fs (8).
 341 .TP
 342 .I blocksize
 343 This relation specifies the default blocksize if the user does not
 344 specify a blocksize on the command line.
 345 .TP
 346 .I lazy_itable_init
 347 This boolean relation specifies whether the inode table should
 348 be lazily initialized.  It only has meaning if the uninit_bg feature is
 349 enabled.  If lazy_itable_init is true and the uninit_bg feature is
 350 enabled,  the inode table will
 351 not be fully initialized by
 352 .BR mke2fs (8).
 353 This speeds up filesystem
 354 initialization noticeably, but it requires the kernel to finish
 355 initializing the filesystem in the background when the filesystem is
 356 first mounted.
 357 .TP
 358 .I lazy_journal_init
 359 This boolean relation specifies whether the journal inode should be
 360 lazily initialized. It only has meaning if the has_journal feature is
 361 enabled. If lazy_journal_init is true, the journal inode will not be
 362 fully zeroed out by
 363 .BR mke2fs .
 364 This speeds up filesystem initialization noticeably, but carries some
 365 small risk if the system crashes before the journal has been overwritten
 366 entirely one time.
 367 .TP
 368 .I journal_location
 369 This relation specifies the location of the journal.
 370 .TP
 371 .I num_backup_sb
 372 This relation indicates whether file systems with the
 373 .B sparse_super2
 374 feature enabled should be created with 0, 1, or 2 backup superblocks.
 375 .TP
 376 .I packed_meta_blocks
 377 This boolean relation specifies whether the allocation bitmaps, inode
 378 table, and journal should be located at the beginning of the file system.
 379 .TP
 380 .I inode_ratio
 381 This relation specifies the default inode ratio if the user does not
 382 specify one on the command line.
 383 .TP
 384 .I inode_size
 385 This relation specifies the default inode size if the user does not
 386 specify one on the command line.
 387 .TP
 388 .I reserved_ratio
 389 This relation specifies the default percentage of filesystem blocks
 390 reserved for the super-user, if the user does not specify one on the command
 391 line.
 392 .TP
 393 .I hash_alg
 394 This relation specifies the default hash algorithm used for the
 395 new filesystems with hashed b-tree directories.  Valid algorithms
 396 accepted are:
 397 .IR legacy ,
 398 .IR half_md4 ,
 399 and
 400 .IR tea .
 401 .TP
 402 .I flex_bg_size
 403 This relation specifies the number of block groups that will be packed
 404 together to create one large virtual block group on an ext4 filesystem.
 405 This improves meta-data locality and performance on meta-data heavy
 406 workloads.  The number of groups must be a power of 2 and may only be
 407 specified if the flex_bg filesystem feature is enabled.
 408 .TP
 409 .I options
 410 This relation specifies additional extended options which should be
 411 treated by
 412 .BR mke2fs (8)
 413 as if they were prepended to the argument of the
 414 .B -E
 415 option.  This can be used to configure the default extended options used
 416 by
 417 .BR mke2fs (8)
 418 on a per-filesystem type basis.
 419 .TP
 420 .I discard
 421 This boolean relation specifies whether the
 422 .BR mke2fs (8)
 423 should attempt to discard device prior to filesystem creation.
 424 .TP
 425 .I cluster_size
 426 This relation specifies the default cluster size if the bigalloc file
 427 system feature is enabled.  It can be overridden via the
 428 .B \-C
 429 command line option to
 430 .BR mke2fs (8)
 431 .TP
 432 .I make_hugefiles
 433 This boolean relation enables the creation of pre-allocated files as
 434 part of formatting the file system.  The extent tree blocks for these
 435 pre-allocated files will be placed near the beginning of the file
 436 system, so that if all of the other metadata blocks are also configured
 437 to be placed near the beginning of the file system (by disabling the
 438 backup superblocks, using the packed_meta_blocks option, etc.), the data
 439 blocks of the pre-allocated files will be contiguous.
 440 .TP
 441 .I hugefiles_dir
 442 This relation specifies the directory where huge files are created,
 443 relative to the filesystem root.
 444 .TP
 445 .I hugefiles_uid
 446 This relation controls the user ownership for all of the files and
 447 directories created by the
 448 .I make_hugefiles
 449 feature.
 450 .TP
 451 .I hugefiles_gid
 452 This relation controls the group ownership for all of the files and
 453 directories created by the
 454 .I make_hugefiles
 455 feature.
 456 .TP
 457 .I hugefiles_umask
 458 This relation specifies the umask used when creating the files and
 459 directories by the
 460 .I make_hugefiles
 461 feature.
 462 .TP
 463 .I num_hugefiles
 464 This relation specifies the number of huge files to be created.  If this
 465 relation is not specified, or is set to zero, and the
 466 .I hugefiles_size
 467 relation is non-zero, then
 468 .I make_hugefiles
 469 will create as many huge files as can fit to fill the entire file system.
 470 .TP
 471 .I hugefiles_slack
 472 This relation specifies how much space should be reserved for other
 473 files.
 474 .TP
 475 .I hugefiles_size
 476 This relation specifies the size of the huge files.  If this relation is
 477 not specified, the default is to fill the entire file system.
 478 .TP
 479 .I hugefiles_align
 480 This relation specifies the alignment for the start block of the huge
 481 files.  It also forces the size of huge files to be a multiple of the
 482 requested alignment.  If this relation is not specified, no alignment
 483 requirement will be imposed on the huge files.
 484 .TP
 485 .I hugefiles_align_disk
 486 This relations specifies whether the alignment should be relative to the
 487 beginning of the hard drive (assuming that the starting offset of the
 488 partition is available to mke2fs).  The default value is false, which
 489 will cause hugefile alignment to be relative to the beginning of the
 490 file system.
 491 .TP
 492 .I hugefiles_name
 493 This relation specifies the base file name for the huge files.
 494 .TP
 495 .I hugefiles_digits
 496 This relation specifies the (zero-padded) width of the field for the
 497 huge file number.
 498 .TP
 499 .I zero_hugefiles
 500 This boolean relation specifies whether or not zero blocks will be
 501 written to the hugefiles while
 502 .BR mke2fs(8)
 503 is creating them.  By default, zero blocks will be written to the huge
 504 files to avoid stale data from being made available to potentially
 505 untrusted user programs, unless the device supports a discard/trim
 506 operation which will take care of zeroing the device blocks.  By setting
 507 .I zero_hugefiles
 508 to false, this step will always be skipped, which can be useful if it is
 509 known that the disk has been previously erased, or if the user programs
 510 that will have access to the huge files are trusted to not reveal stale
 511 data.
 512 .SH THE [devices] STANZA
 513 Each tag in the
 514 .I [devices]
 515 stanza names device name so that per-device defaults can be specified.
 516 .TP
 517 .I fs_type
 518 This relation specifies the default parameter for the
 519 .B \-t
 520 option, if this option isn't specified on the command line.
 521 .TP
 522 .I usage_types
 523 This relation specifies the default parameter for the
 524 .B \-T
 525 option, if this option isn't specified on the command line.
 526 .SH FILES
 527 .TP
 528 .I /etc/mke2fs.conf
 529 The configuration file for
 530 .BR mke2fs (8).
 531 .SH SEE ALSO
 532 .BR mke2fs (8)