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 mke2fs will
 102 wait
 103 .I proceed_delay
 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.
 108 .TP
 109 .I sync_kludge
 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
 113 .I sync_kludge
 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
 118 .I [defaults]
 119 stanza.
 120 .TP
 121 .I fs_type
 122 This relation specifies the default filesystem type if the user does not
 123 specify it via the
 124 .B \-t
 125 option, or if
 126 .B mke2fs
 127 is not started using a program name of the form
 128 .BI mkfs. fs-type\fR.
 129 If both the user and the
 130 .B mke2fs.conf
 131 file do not specify a default filesystem type, mke2fs will use a
 132 default filesystem type of
 133 .IR ext3
 134 if a journal was requested via a command-line option, or
 135 .I ext2
 136 if not.
 137 .TP
 138 .I undo_dir
 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
 143 .IR none ,
 144 .B mke2fs
 145 will not create an undo file.
 146 .PP
 147 In addition, any tags that can be specified in a per-file system tags
 148 subsection as defined below (e.g.,
 149 .IR blocksize ,
 150 .IR hash_alg ,
 151 .IR inode_ratio ,
 152 .IR inode_size ,
 153 .IR reserved_ratio ,
 154 etc.) can also be specified in the
 155 .I defaults
 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
 160 Each tag in the
 161 .I [fs_types]
 162 stanza names a filesystem type or usage type which can be specified via the
 163 .B \-t
 164 or
 165 .B \-T
 166 options to
 167 .BR mke2fs (8),
 168 respectively.
 169 .P
 170 The
 171 .B mke2fs
 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,
 175 .B mke2fs
 176 will look for a subsection in the
 177 .I [fs_types]
 178 stanza corresponding with each entry in the constructed list, with later
 179 entries overriding earlier filesystem or usage types.
 180 For
 181 example, consider the following
 182 .B mke2fs.conf
 183 fragment:
 184 .P
 185 [defaults]
 186 .br
 187         base_features = sparse_super,filetype,resize_inode,dir_index
 188 .br
 189         blocksize = 4096
 190 .br
 191         inode_size = 256
 192 .br
 193         inode_ratio = 16384
 194 .br
 195
 196 .br
 197 [fs_types]
 198 .br
 199         ext3 = {
 200 .br
 201                 features = has_journal
 202 .br
 203         }
 204 .br
 205         ext4 = {
 206 .br
 207                 features = extents,flex_bg
 208 .br
 209                 inode_size = 256
 210 .br
 211         }
 212 .br
 213         small = {
 214 .br
 215                 blocksize = 1024
 216 .br
 217                 inode_ratio = 4096
 218 .br
 219         }
 220 .br
 221         floppy = {
 222 .br
 223                 features = ^resize_inode
 224 .br
 225                 blocksize = 1024
 226 .br
 227                 inode_size = 128
 228 .br
 229         }
 230 .P
 231 If mke2fs started with a program name of
 232 .BR mke2fs.ext4 ,
 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
 235 .B mke2fs
 236 will use a default
 237 usage type of
 238 .IR floppy .
 239 This results in an fs_types list of "ext4, floppy".   Both the ext4
 240 subsection and the floppy subsection define an
 241 .I inode_size
 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.
 245 .P
 246 The exception to this resolution is the
 247 .I features
 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.
 259 .P
 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
 262 .I default
 263 section:
 264 .TP
 265 .I base_features
 266 This relation specifies the features which are initially enabled for this
 267 filesystem type.  Only one
 268 .I base_features
 269 will be used, so if there are multiple entries in the fs_types list
 270 whose subsections define the
 271 .I base_features
 272 relation, only the last will be used by
 273 .BR mke2fs (8).
 274 .TP
 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
 280 .B -i
 281 and
 282 .B -c
 283 command-line options to
 284 .BR tune2fs (8).
 285 .TP
 286 .I errors
 287 Change the behavior of the kernel code when errors are detected.
 288 In all cases, a filesystem error will cause
 289 .BR e2fsck (8)
 290 to check the filesystem on the next boot.
 291 .I errors
 292 can be one of the following:
 293 .RS 1.2i
 294 .TP 1.2i
 295 .B continue
 296 Continue normal execution.
 297 .TP
 298 .B remount-ro
 299 Remount filesystem read-only.
 300 .TP
 301 .B panic
 302 Cause a kernel panic.
 303 .RE
 304 .TP
 305 .I features
 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
 309 .B -O
 310 command-line option to
 311 .BR mke2fs (8);
 312 that is, a feature can be prefixed by a caret ('^') symbol to disable
 313 a named feature.  Each
 314 .I feature
 315 relation specified in the fs_types list will be applied in the order
 316 found in the fs_types list.
 317 .TP
 318 .I force_undo
 319 This boolean relation, if set to a value of true, forces
 320 .B mke2fs
 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.
 324 .TP
 325 .I default_features
 326 This relation specifies set of features which should be enabled or
 327 disabled after applying the features listed in the
 328 .I base_features
 329 and
 330 .I features
 331 relations.  It may be overridden by the
 332 .B -O
 333 command-line option to
 334 .BR mke2fs (8).
 335 .TP
 336 .I auto_64-bit_support
 337 This relation is a boolean which specifies whether
 338 .BR mke2fs (8)
 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
 342 block numbers.
 343 .TP
 344 .I default_mntopts
 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
 347 .B -o
 348 command-line option to
 349 .BR tune2fs (8).
 350 .TP
 351 .I blocksize
 352 This relation specifies the default blocksize if the user does not
 353 specify a blocksize on the command line.
 354 .TP
 355 .I lazy_itable_init
 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
 361 .BR mke2fs (8).
 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
 365 first mounted.
 366 .TP
 367 .I lazy_journal_init
 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
 371 fully zeroed out by
 372 .BR mke2fs .
 373 This speeds up filesystem initialization noticeably, but carries some
 374 small risk if the system crashes before the journal has been overwritten
 375 entirely one time.
 376 .TP
 377 .I journal_location
 378 This relation specifies the location of the journal.
 379 .TP
 380 .I num_backup_sb
 381 This relation indicates whether file systems with the
 382 .B sparse_super2
 383 feature enabled should be created with 0, 1, or 2 backup superblocks.
 384 .TP
 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.
 388 .TP
 389 .I inode_ratio
 390 This relation specifies the default inode ratio if the user does not
 391 specify one on the command line.
 392 .TP
 393 .I inode_size
 394 This relation specifies the default inode size if the user does not
 395 specify one on the command line.
 396 .TP
 397 .I reserved_ratio
 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
 400 line.
 401 .TP
 402 .I hash_alg
 403 This relation specifies the default hash algorithm used for the
 404 new filesystems with hashed b-tree directories.  Valid algorithms
 405 accepted are:
 406 .IR legacy ,
 407 .IR half_md4 ,
 408 and
 409 .IR tea .
 410 .TP
 411 .I flex_bg_size
 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.
 417 .TP
 418 .I options
 419 This relation specifies additional extended options which should be
 420 treated by
 421 .BR mke2fs (8)
 422 as if they were prepended to the argument of the
 423 .B -E
 424 option.  This can be used to configure the default extended options used
 425 by
 426 .BR mke2fs (8)
 427 on a per-filesystem type basis.
 428 .TP
 429 .I discard
 430 This boolean relation specifies whether the
 431 .BR mke2fs (8)
 432 should attempt to discard device prior to filesystem creation.
 433 .TP
 434 .I cluster_size
 435 This relation specifies the default cluster size if the bigalloc file
 436 system feature is enabled.  It can be overridden via the
 437 .B \-C
 438 command line option to
 439 .BR mke2fs (8)
 440 .TP
 441 .I make_hugefiles
 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.
 449 .TP
 450 .I hugefiles_dir
 451 This relation specifies the directory where huge files are created,
 452 relative to the filesystem root.
 453 .TP
 454 .I hugefiles_uid
 455 This relation controls the user ownership for all of the files and
 456 directories created by the
 457 .I make_hugefiles
 458 feature.
 459 .TP
 460 .I hugefiles_gid
 461 This relation controls the group ownership for all of the files and
 462 directories created by the
 463 .I make_hugefiles
 464 feature.
 465 .TP
 466 .I hugefiles_umask
 467 This relation specifies the umask used when creating the files and
 468 directories by the
 469 .I make_hugefiles
 470 feature.
 471 .TP
 472 .I num_hugefiles
 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
 475 .I hugefiles_size
 476 relation is non-zero, then
 477 .I make_hugefiles
 478 will create as many huge files as can fit to fill the entire file system.
 479 .TP
 480 .I hugefiles_slack
 481 This relation specifies how much space should be reserved for other
 482 files.
 483 .TP
 484 .I hugefiles_size
 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.
 487 .TP
 488 .I hugefiles_align
 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.
 493 .TP
 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
 499 file system.
 500 .TP
 501 .I hugefiles_name
 502 This relation specifies the base file name for the huge files.
 503 .TP
 504 .I hugefiles_digits
 505 This relation specifies the (zero-padded) width of the field for the
 506 huge file number.
 507 .TP
 508 .I zero_hugefiles
 509 This boolean relation specifies whether or not zero blocks will be
 510 written to the hugefiles while
 511 .BR mke2fs(8)
 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
 516 .I zero_hugefiles
 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
 520 data.
 521 .SH THE [devices] STANZA
 522 Each tag in the
 523 .I [devices]
 524 stanza names device name so that per-device defaults can be specified.
 525 .TP
 526 .I fs_type
 527 This relation specifies the default parameter for the
 528 .B \-t
 529 option, if this option isn't specified on the command line.
 530 .TP
 531 .I usage_types
 532 This relation specifies the default parameter for the
 533 .B \-T
 534 option, if this option isn't specified on the command line.
 535 .SH FILES
 536 .TP
 537 .I /etc/mke2fs.conf
 538 The configuration file for
 539 .BR mke2fs (8).
 540 .SH SEE ALSO
 541 .BR mke2fs (8)