misc/mke2fs.8.in

   1 .\" -*- nroff -*-
   2 .\" Copyright 1993, 1994, 1995 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 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
   6 .SH NAME
   7 mke2fs \- create an ext2/ext3/ext4 filesystem
   8 .SH SYNOPSIS
   9 .B mke2fs
  10 [
  11 .B \-c
  12 |
  13 .B \-l
  14 .I filename
  15 ]
  16 [
  17 .B \-b
  18 .I block-size
  19 ]
  20 [
  21 .B \-D
  22 ]
  23 [
  24 .B \-f
  25 .I fragment-size
  26 ]
  27 [
  28 .B \-g
  29 .I blocks-per-group
  30 ]
  31 [
  32 .B \-G
  33 .I number-of-groups
  34 ]
  35 [
  36 .B \-i
  37 .I bytes-per-inode
  38 ]
  39 [
  40 .B \-I
  41 .I inode-size
  42 ]
  43 [
  44 .B \-j
  45 ]
  46 [
  47 .B \-J
  48 .I journal-options
  49 ]
  50 [
  51 .B \-N
  52 .I number-of-inodes
  53 ]
  54 [
  55 .B \-d
  56 .I root-directory
  57 ]
  58 [
  59 .B \-n
  60 ]
  61 [
  62 .B \-m
  63 .I reserved-blocks-percentage
  64 ]
  65 [
  66 .B \-o
  67 .I creator-os
  68 ]
  69 [
  70 .B \-O
  71 [^]\fIfeature\fR[,...]
  72 ]
  73 [
  74 .B \-q
  75 ]
  76 [
  77 .B \-r
  78 .I fs-revision-level
  79 ]
  80 [
  81 .B \-E
  82 .I extended-options
  83 ]
  84 [
  85 .B \-v
  86 ]
  87 [
  88 .B \-F
  89 ]
  90 [
  91 .B \-L
  92 .I volume-label
  93 ]
  94 [
  95 .B \-M
  96 .I last-mounted-directory
  97 ]
  98 [
  99 .B \-S
 100 ]
 101 [
 102 .B \-t
 103 .I fs-type
 104 ]
 105 [
 106 .B \-T
 107 .I usage-type
 108 ]
 109 [
 110 .B \-U
 111 .I UUID
 112 ]
 113 [
 114 .B \-V
 115 ]
 116 .I device
 117 [
 118 .I blocks-count
 119 ]
 120 @JDEV@.sp
 121 @JDEV@.B "mke2fs \-O journal_dev"
 122 @JDEV@[
 123 @JDEV@.B \-b
 124 @JDEV@.I block-size
 125 @JDEV@]
 126 .\" No external-journal specific journal options yet (size is ignored)
 127 .\" @JDEV@[
 128 .\" @JDEV@.B \-J
 129 .\" @JDEV@.I journal-options
 130 .\" @JDEV@]
 131 @JDEV@[
 132 @JDEV@.B \-L
 133 @JDEV@.I volume-label
 134 @JDEV@]
 135 @JDEV@[
 136 @JDEV@.B \-n
 137 @JDEV@]
 138 @JDEV@[
 139 @JDEV@.B \-q
 140 @JDEV@]
 141 @JDEV@[
 142 @JDEV@.B \-v
 143 @JDEV@]
 144 @JDEV@.I external-journal
 145 @JDEV@[
 146 @JDEV@.I blocks-count
 147 @JDEV@]
 148 .SH DESCRIPTION
 149 .B mke2fs
 150 is used to create an ext2, ext3, or ext4 filesystem, usually in a disk
 151 partition.
 152 .I device
 153 is the special file corresponding to the device (e.g
 154 .IR /dev/hdXX ).
 155 .I blocks-count
 156 is the number of blocks on the device.  If omitted,
 157 .B mke2fs
 158 automagically figures the file system size.  If called as
 159 .B mkfs.ext3
 160 a journal is created as if the
 161 .B \-j
 162 option was specified.
 163 .PP
 164 The defaults of the parameters for the newly created filesystem, if not
 165 overridden by the options listed below, are controlled by the
 166 .B /etc/mke2fs.conf
 167 configuration file.  See the
 168 .BR mke2fs.conf (5)
 169 manual page for more details.
 170 .SH OPTIONS
 171 .TP
 172 .BI \-b " block-size"
 173 Specify the size of blocks in bytes.  Valid block-size values are 1024,
 174 2048 and 4096 bytes per block.  If omitted,
 175 block-size is heuristically determined by the filesystem size and
 176 the expected usage of the filesystem (see the
 177 .B \-T
 178 option).  If
 179 .I block-size
 180 is preceded by a negative sign ('-'), then
 181 .B mke2fs
 182 will use heuristics to determine the
 183 appropriate block size, with the constraint that the block size will be
 184 at least
 185 .I block-size
 186 bytes.  This is useful for certain hardware devices which require that
 187 the blocksize be a multiple of 2k.
 188 .TP
 189 .B \-c
 190 Check the device for bad blocks before creating the file system.  If
 191 this option is specified twice, then a slower read-write
 192 test is used instead of a fast read-only test.
 193 .TP
 194 .B \-C " cluster-size"
 195 Specify the size of cluster in bytes for filesystems using the bigalloc
 196 feature.  Valid cluster-size values are from 2048 to 256M bytes per
 197 cluster.  This can only be specified if the bigalloc feature is
 198 enabled.  (See the
 199 .B ext4 (5)
 200 man page for more details about bigalloc.)   The default cluster size if
 201 bigalloc is enabled is 16 times the block size.
 202 .TP
 203 .B \-D
 204 Use direct I/O when writing to the disk.  This avoids mke2fs dirtying a
 205 lot of buffer cache memory, which may impact other applications running
 206 on a busy server.  This option will cause mke2fs to run much more
 207 slowly, however, so there is a tradeoff to using direct I/O.
 208 .TP
 209 .BI \-E " extended-options"
 210 Set extended options for the filesystem.  Extended options are comma
 211 separated, and may take an argument using the equals ('=') sign.  The
 212 .B \-E
 213 option used to be
 214 .B \-R
 215 in earlier versions of
 216 .BR mke2fs .
 217 The
 218 .B \-R
 219 option is still accepted for backwards compatibility, but is deprecated.
 220 The following extended options are supported:
 221 .RS 1.2i
 222 .TP
 223 .BI mmp_update_interval= interval
 224 Adjust the initial MMP update interval to
 225 .I interval
 226 seconds.  Specifying an
 227 .I interval
 228 of 0 means to use the default interval.  The specified interval must
 229 be less than 300 seconds.  Requires that the
 230 .B mmp
 231 feature be enabled.
 232 .TP
 233 .BI stride= stride-size
 234 Configure the filesystem for a RAID array with
 235 .I stride-size
 236 filesystem blocks. This is the number of blocks read or written to disk
 237 before moving to the next disk, which is sometimes referred to as the
 238 .I chunk size.
 239 This mostly affects placement of filesystem metadata like bitmaps at
 240 .B mke2fs
 241 time to avoid placing them on a single disk, which can hurt performance.
 242 It may also be used by the block allocator.
 243 .TP
 244 .BI stripe_width= stripe-width
 245 Configure the filesystem for a RAID array with
 246 .I stripe-width
 247 filesystem blocks per stripe. This is typically stride-size * N, where
 248 N is the number of data-bearing disks in the RAID (e.g. for RAID 5 there is one
 249 parity disk, so N will be the number of disks in the array minus 1).
 250 This allows the block allocator to prevent read-modify-write of the
 251 parity in a RAID stripe if possible when the data is written.
 252 .TP
 253 .BI offset= offset
 254 Create the filesystem at an offset from the beginning of the device or
 255 file.  This can be useful when creating disk images for virtual machines.
 256 .TP
 257 .BI resize= max-online-resize
 258 Reserve enough space so that the block group descriptor table can grow
 259 to support a filesystem that has
 260 .I max-online-resize
 261 blocks.
 262 .TP
 263 .B lazy_itable_init\fR[\fB= \fI<0 to disable, 1 to enable>\fR]
 264 If enabled and the uninit_bg feature is enabled, the inode table will
 265 not be fully initialized by
 266 .BR mke2fs .
 267 This speeds up filesystem
 268 initialization noticeably, but it requires the kernel to finish
 269 initializing the filesystem in the background when the filesystem is
 270 first mounted.  If the option value is omitted, it defaults to 1 to
 271 enable lazy inode table zeroing.
 272 .TP
 273 .B lazy_journal_init\fR[\fB= \fI<0 to disable, 1 to enable>\fR]
 274 If enabled, the journal inode will not be fully zeroed out by
 275 .BR mke2fs .
 276 This speeds up filesystem initialization noticeably, but carries some
 277 small risk if the system crashes before the journal has been overwritten
 278 entirely one time.  If the option value is omitted, it defaults to 1 to
 279 enable lazy journal inode zeroing.
 280 .TP
 281 .BI num_backup_sb= <0|1|2>
 282 If the
 283 .B sparse_super2
 284 file system feature is enabled this option controls whether there will
 285 be 0, 1, or 2 backup superblocks created in the file system.
 286 .TP
 287 .B packed_meta_blocks\fR[\fB= \fI<0 to disable, 1 to enable>\fR]
 288 Place the allocation bitmaps and the inode table at the beginning of the
 289 disk.  This option requires that the flex_bg file system feature to be
 290 enabled in order for it to have effect, and will also create the journal
 291 at the beginning of the file system.  This option is useful for flash
 292 devices that use SLC flash at the beginning of the disk.
 293 It also maximizes the range of contiguous data blocks, which
 294 can be useful for certain specialized use cases, such as supported
 295 Shingled Drives.
 296 .TP
 297 .BI root_owner [=uid:gid]
 298 Specify the numeric user and group ID of the root directory.  If no UID:GID
 299 is specified, use the user and group ID of the user running \fBmke2fs\fR.
 300 In \fBmke2fs\fR 1.42 and earlier the UID and GID of the root directory were
 301 set by default to the UID and GID of the user running the mke2fs command.
 302 The \fBroot_owner=\fR option allows explicitly specifying these values,
 303 and avoid side-effects for users that do not expect the contents of the
 304 filesystem to change based on the user running \fBmke2fs\fR.
 305 .TP
 306 .B test_fs
 307 Set a flag in the filesystem superblock indicating that it may be
 308 mounted using experimental kernel code, such as the ext4dev filesystem.
 309 .TP
 310 .BI discard
 311 Attempt to discard blocks at mkfs time (discarding blocks initially is useful
 312 on solid state devices and sparse / thin-provisioned storage). When the device
 313 advertises that discard also zeroes data (any subsequent read after the discard
 314 and before write returns zero), then mark all not-yet-zeroed inode tables as
 315 zeroed. This significantly speeds up filesystem initialization. This is set
 316 as default.
 317 .TP
 318 .BI nodiscard
 319 Do not attempt to discard blocks at mkfs time.
 320 @QUOTA_MAN_COMMENT@.TP
 321 @QUOTA_MAN_COMMENT@.BI quotatype
 322 @QUOTA_MAN_COMMENT@Specify which quota type ('usr' or 'grp') is to be
 323 @QUOTA_MAN_COMMENT@initialized. This option has effect only if the
 324 @QUOTA_MAN_COMMENT@.B quota
 325 @QUOTA_MAN_COMMENT@feature is set. Without this extended option, the default
 326 @QUOTA_MAN_COMMENT@behavior is to initialize both user and group quotas.
 327 .RE
 328 .TP
 329 .BI \-f " fragment-size"
 330 Specify the size of fragments in bytes.
 331 .TP
 332 .B \-F
 333 Force
 334 .B mke2fs
 335 to create a filesystem, even if the specified device is not a partition
 336 on a block special device, or if other parameters do not make sense.
 337 In order to force
 338 .B mke2fs
 339 to create a filesystem even if the filesystem appears to be in use
 340 or is mounted (a truly dangerous thing to do), this option must be
 341 specified twice.
 342 .TP
 343 .BI \-g " blocks-per-group"
 344 Specify the number of blocks in a block group.  There is generally no
 345 reason for the user to ever set this parameter, as the default is optimal
 346 for the filesystem.  (For administrators who are creating
 347 filesystems on RAID arrays, it is preferable to use the
 348 .I stride
 349 RAID parameter as part of the
 350 .B \-E
 351 option rather than manipulating the number of blocks per group.)
 352 This option is generally used by developers who
 353 are developing test cases.
 354 .IP
 355 If the bigalloc feature is enabled, the
 356 .B \-g
 357 option will specify the number of clusters in a block group.
 358 .TP
 359 .BI \-G " number-of-groups"
 360 Specify the number of block groups that will be packed together to
 361 create a larger virtual block group (or "flex_bg group") in an
 362 ext4 filesystem.  This improves meta-data locality and performance
 363 on meta-data heavy workloads.  The number of groups must be a power
 364 of 2 and may only be specified if the
 365 .B flex_bg
 366 filesystem feature is enabled.
 367 .TP
 368 .BI \-i " bytes-per-inode"
 369 Specify the bytes/inode ratio.
 370 .B mke2fs
 371 creates an inode for every
 372 .I bytes-per-inode
 373 bytes of space on the disk.  The larger the
 374 .I bytes-per-inode
 375 ratio, the fewer inodes will be created.  This value generally shouldn't
 376 be smaller than the blocksize of the filesystem, since in that case more
 377 inodes would be made than can ever be used.  Be warned that it is not
 378 possible to change this ratio on a filesystem after it is created, so be
 379 careful deciding the correct value for this parameter.  Note that resizing
 380 a filesystem changes the numer of inodes to maintain this ratio.
 381 .TP
 382 .BI \-I " inode-size"
 383 Specify the size of each inode in bytes.
 384 The
 385 .I inode-size
 386 value must be a power of 2 larger or equal to 128.  The larger the
 387 .I inode-size
 388 the more space the inode table will consume, and this reduces the usable
 389 space in the filesystem and can also negatively impact performance.
 390 It is not
 391 possible to change this value after the filesystem is created.
 392 .IP
 393 In kernels after 2.6.10 and some
 394 earlier vendor kernels it is possible to utilize inodes larger than
 395 128 bytes to store
 396 extended attributes for improved performance.
 397 Extended attributes
 398 stored in large inodes are not visible with older kernels, and such
 399 filesystems will not be mountable with 2.4 kernels at all.
 400 .IP
 401 The default inode size is controlled by the
 402 .BR mke2fs.conf (5)
 403 file.  In the
 404 .B mke2fs.conf
 405 file shipped with e2fsprogs, the default inode size is 256 bytes for
 406 most file systems, except for small file systems where the inode size
 407 will be 128 bytes.
 408 .TP
 409 .B \-j
 410 Create the filesystem with an ext3 journal.  If the
 411 .B \-J
 412 option is not specified, the default journal parameters will be used to
 413 create an appropriately sized journal (given the size of the filesystem)
 414 stored within the filesystem.  Note that you must be using a kernel
 415 which has ext3 support in order to actually make use of the journal.
 416 .TP
 417 .BI \-J " journal-options"
 418 Create the ext3 journal using options specified on the command-line.
 419 Journal options are comma
 420 separated, and may take an argument using the equals ('=')  sign.
 421 The following journal options are supported:
 422 .RS 1.2i
 423 .TP
 424 .BI size= journal-size
 425 Create an internal journal (i.e., stored inside the filesystem) of size
 426 .I journal-size
 427 megabytes.
 428 The size of the journal must be at least 1024 filesystem blocks
 429 (i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.)
 430 and may be no more than 10,240,000 filesystem blocks or half the total
 431 file system size (whichever is smaller)
 432 .TP
 433 .BI location =journal-location
 434 Specify the location of the journal.  The argument
 435 .I journal-location
 436 can either be specified as a block number, or if the number has a units
 437 suffix (e.g., 'M', 'G', etc.) interpret it as the offset from the
 438 beginning of the file system.
 439 @JDEV@.TP
 440 @JDEV@.BI device= external-journal
 441 @JDEV@Attach the filesystem to the journal block device located on
 442 @JDEV@.IR external-journal .
 443 @JDEV@The external
 444 @JDEV@journal must already have been created using the command
 445 @JDEV@.IP
 446 @JDEV@.B mke2fs -O journal_dev
 447 @JDEV@.I external-journal
 448 @JDEV@.IP
 449 @JDEV@Note that
 450 @JDEV@.I external-journal
 451 @JDEV@must have been created with the
 452 @JDEV@same block size as the new filesystem.
 453 @JDEV@In addition, while there is support for attaching
 454 @JDEV@multiple filesystems to a single external journal,
 455 @JDEV@the Linux kernel and
 456 @JDEV@.BR e2fsck (8)
 457 @JDEV@do not currently support shared external journals yet.
 458 @JDEV@.IP
 459 @JDEV@Instead of specifying a device name directly,
 460 @JDEV@.I external-journal
 461 @JDEV@can also be specified by either
 462 @JDEV@.BI LABEL= label
 463 @JDEV@or
 464 @JDEV@.BI UUID= UUID
 465 @JDEV@to locate the external journal by either the volume label or UUID
 466 @JDEV@stored in the ext2 superblock at the start of the journal.  Use
 467 @JDEV@.BR dumpe2fs (8)
 468 @JDEV@to display a journal device's volume label and UUID.  See also the
 469 @JDEV@.B -L
 470 @JDEV@option of
 471 @JDEV@.BR tune2fs (8).
 472 .RE
 473 @JDEV@.IP
 474 @JDEV@Only one of the
 475 @JDEV@.BR size " or " device
 476 @JDEV@options can be given for a filesystem.
 477 .TP
 478 .BI \-l " filename"
 479 Read the bad blocks list from
 480 .IR filename .
 481 Note that the block numbers in the bad block list must be generated
 482 using the same block size as used by
 483 .BR mke2fs .
 484 As a result, the
 485 .B \-c
 486 option to
 487 .B mke2fs
 488 is a much simpler and less error-prone method of checking a disk for bad
 489 blocks before formatting it, as
 490 .B mke2fs
 491 will automatically pass the correct parameters to the
 492 .B badblocks
 493 program.
 494 .TP
 495 .BI \-L " new-volume-label"
 496 Set the volume label for the filesystem to
 497 .IR new-volume-label .
 498 The maximum length of the
 499 volume label is 16 bytes.
 500 .TP
 501 .BI \-m " reserved-blocks-percentage"
 502 Specify the percentage of the filesystem blocks reserved for
 503 the super-user.  This avoids fragmentation, and allows root-owned
 504 daemons, such as
 505 .BR syslogd (8),
 506 to continue to function correctly after non-privileged processes are
 507 prevented from writing to the filesystem.  The default percentage
 508 is 5%.
 509 .TP
 510 .BI \-M " last-mounted-directory"
 511 Set the last mounted directory for the filesystem.  This might be useful
 512 for the sake of utilities that key off of the last mounted directory to
 513 determine where the filesystem should be mounted.
 514 .TP
 515 .B \-n
 516 Causes
 517 .B mke2fs
 518 to not actually create a filesystem, but display what it
 519 would do if it were to create a filesystem.  This can be used to
 520 determine the location of the backup superblocks for a particular
 521 filesystem, so long as the
 522 .B mke2fs
 523 parameters that were passed when the
 524 filesystem was originally created are used again.  (With the
 525 .B \-n
 526 option added, of course!)
 527 .TP
 528 .BI \-N " number-of-inodes"
 529 Overrides the default calculation of the number of inodes that should be
 530 reserved for the filesystem (which is based on the number of blocks and
 531 the
 532 .I bytes-per-inode
 533 ratio).  This allows the user to specify the number
 534 of desired inodes directly.
 535 .TP
 536 .BI \-d " root-directory"
 537 Add the files from the root-directory to the filesystem.
 538 .TP
 539 .BI \-o " creator-os"
 540 Overrides the default value of the "creator operating system" field of the
 541 filesystem.  The creator field is set by default to the name of the OS the
 542 .B mke2fs
 543 executable was compiled for.
 544 .TP
 545 .B "\-O \fR[^]\fIfeature\fR[,...]"
 546 Create a filesystem with the given features (filesystem options),
 547 overriding the default filesystem options.  The features that are
 548 enabled by default are specified by the
 549 .I base_features
 550 relation, either in the
 551 .I [defaults]
 552 section in the
 553 .B /etc/mke2fs.conf
 554 configuration file,
 555 or in the
 556 .I [fs_types]
 557 subsections for the usage types as specified by the
 558 .B \-T
 559 option, further modified by the
 560 .I features
 561 relation found in the
 562 .I [fs_types]
 563 subsections for the filesystem and usage types.  See the
 564 .BR mke2fs.conf (5)
 565 manual page for more details.
 566 The filesystem type-specific configuration setting found in the
 567 .I [fs_types]
 568 section will override the global default found in
 569 .IR [defaults] .
 570 .sp
 571 The filesystem feature set will be further edited
 572 using either the feature set specified by this option,
 573 or if this option is not given, by the
 574 .I default_features
 575 relation for the filesystem type being created, or in the
 576 .I [defaults]
 577 section of the configuration file.
 578 .sp
 579 The filesystem feature set is comprised of a list of features, separated
 580 by commas, that are to be enabled.  To disable a feature, simply
 581 prefix the feature name with a caret ('^') character.
 582 Features with dependencies will not be removed successfully.
 583 The pseudo-filesystem feature "none" will clear all filesystem features.
 584 .TP
 585 For more information about the features which can be set, please see
 586 the manual page
 587 .BR ext4 (5).
 588 .TP
 589 .B \-q
 590 Quiet execution.  Useful if
 591 .B mke2fs
 592 is run in a script.
 593 .TP
 594 .BI \-r " revision"
 595 Set the filesystem revision for the new filesystem.  Note that 1.2
 596 kernels only support revision 0 filesystems.  The default is to
 597 create revision 1 filesystems.
 598 .TP
 599 .B \-S
 600 Write superblock and group descriptors only.  This is useful if all of
 601 the superblock and backup superblocks are corrupted, and a last-ditch
 602 recovery method is desired.  It causes
 603 .B mke2fs
 604 to reinitialize the
 605 superblock and group descriptors, while not touching the inode table
 606 and the block and inode bitmaps.  The
 607 .B e2fsck
 608 program should be run immediately after this option is used, and there
 609 is no guarantee that any data will be salvageable.  It is critical to
 610 specify the correct filesystem blocksize when using this option,
 611 or there is no chance of recovery.
 612 .\" .TP
 613 .\" .BI \-t " test"
 614 .\" Check the device for bad blocks before creating the file system
 615 .\" using the specified test.
 616 .TP
 617 .BI \-t " fs-type"
 618 Specify the filesystem type (i.e., ext2, ext3, ext4, etc.) that is
 619 to be created.
 620 If this option is not specified,
 621 .B mke2fs
 622 will pick a default either via how
 623 the command was run (for example, using a name of the form mkfs.ext2,
 624 mkfs.ext3, etc.) or via a default as defined by the
 625 .B /etc/mke2fs.conf
 626 file.   This option controls which filesystem options are used by
 627 default, based on the
 628 .B fstypes
 629 configuration stanza in
 630 .BR /etc/mke2fs.conf .
 631 .sp
 632 If the
 633 .B \-O
 634 option is used to explicitly add or remove filesystem options that
 635 should be set in the newly created filesystem, the
 636 resulting filesystem may not be supported by the requested
 637 .IR fs-type .
 638 (e.g., "\fBmke2fs \-t ext3 \-O extent /dev/sdXX\fR" will create a
 639 filesystem that is not supported by the ext3 implementation as found in
 640 the Linux kernel; and "\fBmke2fs \-t ext3 \-O ^has_journal /dev/hdXX\fR"
 641 will create a filesystem that does not have a journal and hence will not
 642 be supported by the ext3 filesystem code in the Linux kernel.)
 643 .TP
 644 .BI \-T " usage-type[,...]"
 645 Specify how the filesystem is going to be used, so that
 646 .B mke2fs
 647 can choose optimal filesystem parameters for that use.  The usage
 648 types that are supported are defined in the configuration file
 649 .BR /etc/mke2fs.conf .
 650 The user may specify one or more usage types
 651 using a comma separated list.
 652 .sp
 653 If this option is is not specified,
 654 .B mke2fs
 655 will pick a single default usage type based on the size of the filesystem to
 656 be created.  If the filesystem size is less than or equal to 3 megabytes,
 657 .B mke2fs
 658 will use the filesystem type
 659 .IR floppy .
 660 If the filesystem size is greater than 3 but less than or equal to
 661 512 megabytes,
 662 .BR mke2fs (8)
 663 will use the filesystem type
 664 .IR small .
 665 If the filesystem size is greater than or equal to 4 terabytes but less than
 666 16 terabytes,
 667 .BR mke2fs (8)
 668 will use the filesystem type
 669 .IR big .
 670 If the filesystem size is greater than or equal to 16 terabytes,
 671 .BR mke2fs (8)
 672 will use the filesystem type
 673 .IR huge .
 674 Otherwise,
 675 .BR mke2fs (8)
 676 will use the default filesystem type
 677 .IR default .
 678 .TP
 679 .BI \-U " UUID"
 680 Create the filesystem with the specified UUID.
 681 .TP
 682 .B \-v
 683 Verbose execution.
 684 .TP
 685 .B \-V
 686 Print the version number of
 687 .B mke2fs
 688 and exit.
 689 .SH ENVIRONMENT
 690 .TP
 691 .BI MKE2FS_SYNC
 692 If set to non-zero integer value, its value is used to determine how often
 693 .BR sync (2)
 694 is called during inode table initialization.
 695 .TP
 696 .BI MKE2FS_CONFIG
 697 Determines the location of the configuration file (see
 698 .BR mke2fs.conf (5)).
 699 .TP
 700 .BI MKE2FS_FIRST_META_BG
 701 If set to non-zero integer value, its value is used to determine first meta
 702 block group. This is mostly for debugging purposes.
 703 .TP
 704 .BI MKE2FS_DEVICE_SECTSIZE
 705 If set to non-zero integer value, its value is used to determine physical
 706 sector size of the
 707 .IR device .
 708 .TP
 709 .BI MKE2FS_SKIP_CHECK_MSG
 710 If set, do not show the message of filesystem automatic check caused by
 711 mount count or check interval.
 712 .SH AUTHOR
 713 This version of
 714 .B mke2fs
 715 has been written by Theodore Ts'o <tytso@mit.edu>.
 716 .SH BUGS
 717 .B mke2fs
 718 accepts the
 719 .B \-f
 720 option but currently ignores it because the second
 721 extended file system does not support fragments yet.
 722 .br
 723 There may be other ones.  Please, report them to the author.
 724 .SH AVAILABILITY
 725 .B mke2fs
 726 is part of the e2fsprogs package and is available from
 727 http://e2fsprogs.sourceforge.net.
 728 .SH SEE ALSO
 729 .BR mke2fs.conf (5),
 730 .BR badblocks (8),
 731 .BR dumpe2fs (8),
 732 .BR e2fsck (8),
 733 .BR tune2fs (8),
 734 .BR ext4 (5)