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