mke2fs man page on Archlinux

Man page or keyword search:  
man Server   11224 pages
apropos Keyword Search (all sections)
Output format
Archlinux logo
[printable version]

MKE2FS(8)							     MKE2FS(8)

       mke2fs - create an ext2/ext3/ext4 filesystem

       mke2fs [ -c | -l filename ] [ -b block-size ] [ -D ] [ -f fragment-size
       ] [ -g blocks-per-group ] [ -G number-of-groups ] [ -i  bytes-per-inode
       ] [ -I inode-size ] [ -j ] [ -J journal-options ] [ -N number-of-inodes
       ] [ -n ] [ -m reserved-blocks-percentage ] [ -o creator-os ] [ -O  fea‐
       ture[,...]  ] [ -q ] [ -r fs-revision-level ] [ -E extended-options ] [
       -v ] [ -F ] [ -L volume-label ] [ -M last-mounted-directory ] [ -S ]  [
       -t fs-type ] [ -T usage-type ] [ -U UUID ] [ -V ] device [ blocks-count

       mke2fs -O journal_dev [ -b block-size ] [ -L volume-label ] [ -n ] [ -q
       ] [ -v ] external-journal [ blocks-count ]

       mke2fs  is used to create an ext2, ext3, or ext4 filesystem, usually in
       a disk partition.  device is the	 special  file	corresponding  to  the
       device  (e.g  /dev/hdXX).   blocks-count is the number of blocks on the
       device.	If omitted, mke2fs automagically figures the file system size.
       If  called  as  mkfs.ext3  a journal is created as if the -j option was

       The defaults of the parameters for the newly created filesystem, if not
       overridden   by	the  options  listed  below,  are  controlled  by  the
       /etc/mke2fs.conf configuration file.   See  the	mke2fs.conf(5)	manual
       page for more details.

       -b block-size
	      Specify  the  size  of blocks in bytes.  Valid block-size values
	      are 1024, 2048 and 4096 bytes per block.	If omitted, block-size
	      is  heuristically	 determined  by	 the  filesystem  size and the
	      expected usage of the filesystem (see the -T option).  If block-
	      size  is preceded by a negative sign ('-'), then mke2fs will use
	      heuristics to determine the appropriate  block  size,  with  the
	      constraint  that	the  block  size  will	be at least block-size
	      bytes.  This  is	useful	for  certain  hardware	devices	 which
	      require that the blocksize be a multiple of 2k.

       -c     Check the device for bad blocks before creating the file system.
	      If this option is specified twice, then a slower read-write test
	      is used instead of a fast read-only test.

       -C  cluster-size
	      Specify  the  size of cluster in bytes for filesystems using the
	      bigalloc feature.	 Valid cluster-size values are	from  2048  to
	      256M  bytes  per	cluster.   This	 can  only be specified if the
	      bigalloc feature is enabled.  (See the ext4  (5)	man  page  for
	      more  details  about  bigalloc.)	  The  default cluster size if
	      bigalloc is enabled is 16 times the block size.

       -D     Use direct I/O when writing to the  disk.	  This	avoids	mke2fs
	      dirtying	a  lot	of buffer cache memory, which may impact other
	      applications running on a busy server.  This option  will	 cause
	      mke2fs  to run much more slowly, however, so there is a tradeoff
	      to using direct I/O.

       -E extended-options
	      Set extended options for the filesystem.	Extended  options  are
	      comma separated, and may take an argument using the equals ('=')
	      sign.  The -E option used	 to  be	 -R  in	 earlier  versions  of
	      mke2fs.	The -R option is still accepted for backwards compati‐
	      bility, but is deprecated.  The following extended  options  are

			  Adjust  the  initial MMP update interval to interval
			  seconds.  Specifying an interval of 0 means  to  use
			  the  default	interval.  The specified interval must
			  be less than 300 seconds.   Requires	that  the  mmp
			  feature be enabled.

			  Configure  the  filesystem  for  a  RAID  array with
			  stride-size filesystem blocks. This is the number of
			  blocks  read or written to disk before moving to the
			  next disk, which is sometimes	 referred  to  as  the
			  chunk	  size.	  This	mostly	affects	 placement  of
			  filesystem metadata like bitmaps at mke2fs  time  to
			  avoid	 placing them on a single disk, which can hurt
			  performance.	It may also be used by the block allo‐

			  Configure  the  filesystem  for  a  RAID  array with
			  stripe-width filesystem blocks per stripe.  This  is
			  typically  stride-size * N, where N is the number of
			  data-bearing disks in the  RAID  (e.g.  for  RAID  5
			  there is one parity disk, so N will be the number of
			  disks in the array minus 1).	This allows the	 block
			  allocator to prevent read-modify-write of the parity
			  in a RAID stripe if possible when the data is	 writ‐

			  Reserve   enough  space  so  that  the  block	 group
			  descriptor table can grow to	support	 a  filesystem
			  that has max-online-resize blocks.

		   lazy_itable_init[= <0 to disable, 1 to enable>]
			  If enabled and the uninit_bg feature is enabled, the
			  inode table will not be fully initialized by mke2fs.
			  This speeds up filesystem initialization noticeably,
			  but it requires the kernel  to  finish  initializing
			  the filesystem in the background when the filesystem
			  is first mounted.  If the option value  is  omitted,
			  it defaults to 1 to enable lazy inode table zeroing.

		   lazy_journal_init[= <0 to disable, 1 to enable>]
			  If  enabled,	the  journal  inode  will not be fully
			  zeroed out by mke2fs.	  This	speeds	up  filesystem
			  initialization  noticeably,  but  carries some small
			  risk if the system crashes before  the  journal  has
			  been	overwritten  entirely one time.	 If the option
			  value is omitted, it defaults to 1  to  enable  lazy
			  journal inode zeroing.

			  Specify  the	numeric	 user and group ID of the root
			  directory.  If no UID:GID is specified, use the user
			  and  group ID of the user running mke2fs.  In mke2fs
			  1.42 and earlier the UID and GID of the root	direc‐
			  tory	were  set by default to the UID and GID of the
			  user running the mke2fs  command.   The  root_owner=
			  option  allows  explicitly  specifying these values,
			  and avoid side-effects for users that do not	expect
			  the  contents	 of  the filesystem to change based on
			  the user running mke2fs.

			  Set a flag in the filesystem	superblock  indicating
			  that	it  may	 be  mounted using experimental kernel
			  code, such as the ext4dev filesystem.

			  Attempt to discard blocks at mkfs  time  (discarding
			  blocks  initially  is	 useful on solid state devices
			  and sparse /	thin-provisioned  storage).  When  the
			  device advertises that discard also zeroes data (any
			  subsequent read after the discard and	 before	 write
			  returns  zero),  then	 mark all not-yet-zeroed inode
			  tables  as  zeroed.  This  significantly  speeds  up
			  filesystem initialization. This is set as default.

			  Do not attempt to discard blocks at mkfs time.

       -f fragment-size
	      Specify the size of fragments in bytes.

       -F     Force  mke2fs  to	 create	 a  filesystem,	 even if the specified
	      device is not a partition on a block special device, or if other
	      parameters  do not make sense.  In order to force mke2fs to cre‐
	      ate a filesystem even if the filesystem appears to be in use  or
	      is  mounted (a truly dangerous thing to do), this option must be
	      specified twice.

       -g blocks-per-group
	      Specify the number of blocks in a block group.  There is	gener‐
	      ally  no	reason for the user to ever set this parameter, as the
	      default is optimal for the filesystem.  (For administrators  who
	      are creating filesystems on RAID arrays, it is preferable to use
	      the stride RAID parameter as part of the -E option  rather  than
	      manipulating  the	 number	 of blocks per group.)	This option is
	      generally used by developers who are developing test cases.

	      If the bigalloc feature is enabled, the -g option	 will  specify
	      the number of clusters in a block group.

       -G number-of-groups
	      Specify  the number of block groups that will be packed together
	      to create a larger virtual block group (or "flex_bg  group")  in
	      an  ext4	filesystem.  This improves meta-data locality and per‐
	      formance on meta-data heavy workloads.   The  number  of	groups
	      must  be	a  power of 2 and may only be specified if the flex_bg
	      filesystem feature is enabled.

       -i bytes-per-inode
	      Specify the bytes/inode ratio.   mke2fs  creates	an  inode  for
	      every  bytes-per-inode  bytes  of space on the disk.  The larger
	      the bytes-per-inode ratio, the fewer  inodes  will  be  created.
	      This  value generally shouldn't be smaller than the blocksize of
	      the filesystem, since in that case more  inodes  would  be  made
	      than  can	 ever  be  used.  Be warned that it is not possible to
	      change this ratio on a filesystem after it  is  created,	so  be
	      careful  deciding	 the  correct  value for this parameter.  Note
	      that resizing a filesystem changes the numer of inodes to	 main‐
	      tain this ratio.

       -I inode-size
	      Specify  the  size of each inode in bytes.  The inode-size value
	      must be a power of 2 larger or equal to  128.   The  larger  the
	      inode-size the more space the inode table will consume, and this
	      reduces the usable space in the filesystem and  can  also	 nega‐
	      tively  impact  performance.   It is not possible to change this
	      value after the filesystem is created.

	      In kernels after 2.6.10 and some earlier vendor  kernels	it  is
	      possible	to  utilize  inodes  larger  than  128	bytes to store
	      extended	attributes   for   improved   performance.    Extended
	      attributes  stored  in  large  inodes are not visible with older
	      kernels, and such filesystems will not  be  mountable  with  2.4
	      kernels at all.

	      The default inode size is controlled by the mke2fs.conf(5) file.
	      In the mke2fs.conf file  shipped	with  e2fsprogs,  the  default
	      inode  size is 256 bytes for most file systems, except for small
	      file systems where the inode size will be 128 bytes.

       -j     Create the filesystem with an ext3 journal.  If the -J option is
	      not  specified,  the  default journal parameters will be used to
	      create an appropriately sized journal (given  the	 size  of  the
	      filesystem) stored within the filesystem.	 Note that you must be
	      using a kernel which has ext3 support in order to actually  make
	      use of the journal.

       -J journal-options
	      Create  the ext3 journal using options specified on the command-
	      line.  Journal options are comma	separated,  and	 may  take  an
	      argument	using  the  equals ('=')  sign.	 The following journal
	      options are supported:

			  Create an internal journal (i.e., stored inside  the
			  filesystem)  of  size	 journal-size  megabytes.  The
			  size of the journal must be at least 1024 filesystem
			  blocks  (i.e.,  1MB if using 1k blocks, 4MB if using
			  4k blocks, etc.)  and may be no more than 10,240,000
			  filesystem blocks or half the total file system size
			  (whichever is smaller)

			  Attach the filesystem to the	journal	 block	device
			  located  on  external-journal.  The external journal
			  must already have been created using the command

			  mke2fs -O journal_dev external-journal

			  Note that external-journal must  have	 been  created
			  with	the same block size as the new filesystem.  In
			  addition, while there is support for attaching  mul‐
			  tiple	 filesystems to a single external journal, the
			  Linux kernel and e2fsck(8) do not currently  support
			  shared external journals yet.

			  Instead of specifying a device name directly, exter‐
			  nal-journal  can  also  be   specified   by	either
			  LABEL=label  or  UUID=UUID  to  locate  the external
			  journal by either the volume label or UUID stored in
			  the  ext2  superblock	 at  the start of the journal.
			  Use dumpe2fs(8) to display a journal device's volume
			  label	  and	UUID.	See  also  the	-L  option  of

	      Only one of the size or  device  options	can  be	 given	for  a

       -l filename
	      Read  the	 bad  blocks  list from filename.  Note that the block
	      numbers in the bad block list must be generated using  the  same
	      block  size  as  used  by mke2fs.	 As a result, the -c option to
	      mke2fs is a much simpler and less error-prone method of checking
	      a disk for bad blocks before formatting it, as mke2fs will auto‐
	      matically pass the correct parameters to the badblocks program.

       -L new-volume-label
	      Set the volume label for	the  filesystem	 to  new-volume-label.
	      The maximum length of the volume label is 16 bytes.

       -m reserved-blocks-percentage
	      Specify the percentage of the filesystem blocks reserved for the
	      super-user.  This avoids fragmentation,  and  allows  root-owned
	      daemons,	such  as syslogd(8), to continue to function correctly
	      after non-privileged processes are prevented from writing to the
	      filesystem.  The default percentage is 5%.

       -M last-mounted-directory
	      Set  the	last mounted directory for the filesystem.  This might
	      be useful for the sake of utilities that key  off	 of  the  last
	      mounted  directory  to  determine where the filesystem should be

       -n     Causes mke2fs to not actually create a filesystem,  but  display
	      what it would do if it were to create a filesystem.  This can be
	      used to determine the location of the backup superblocks	for  a
	      particular  filesystem,  so  long	 as the mke2fs parameters that
	      were passed when the filesystem was originally created are  used
	      again.  (With the -n option added, of course!)

       -N number-of-inodes
	      Overrides	 the  default calculation of the number of inodes that
	      should be reserved for the filesystem (which  is	based  on  the
	      number  of  blocks  and the bytes-per-inode ratio).  This allows
	      the user to specify the number of desired inodes directly.

       -o creator-os
	      Overrides the default value of the  "creator  operating  system"
	      field of the filesystem.	The creator field is set by default to
	      the name of the OS the mke2fs executable was compiled for.

       -O feature[,...]
	      Create  a	 filesystem  with  the	given	features   (filesystem
	      options),	 overriding  the default filesystem options.  The fea‐
	      tures that are enabled by default are specified by the base_fea‐
	      tures   relation,	 either	 in  the  [defaults]  section  in  the
	      /etc/mke2fs.conf configuration file, or in the  [fs_types]  sub‐
	      sections for the usage types as specified by the -T option, fur‐
	      ther modified by the features relation found in  the  [fs_types]
	      subsections  for	the  filesystem	 and  usage  types.   See  the
	      mke2fs.conf(5) manual page for  more  details.   The  filesystem
	      type-specific configuration setting found in the [fs_types] sec‐
	      tion will override the global default found in [defaults].

	      The filesystem feature set will be further edited	 using	either
	      the  feature  set specified by this option, or if this option is
	      not given, by the default_features relation for  the  filesystem
	      type being created, or in the [defaults] section of the configu‐
	      ration file.

	      The filesystem feature set is comprised of a list	 of  features,
	      separated	 by commas, that are to be enabled.  To disable a fea‐
	      ture, simply prefix the feature name with a  caret  ('^')	 or  a
	      minus  ('-')  character.	Features with dependencies will not be
	      removed successfully.  The pseudo-filesystem feature "none" will
	      clear all filesystem features.

       For more information about the features which can be set, please see
	      the manual page ext4(5).

       -q     Quiet execution.	Useful if mke2fs is run in a script.

       -r revision
	      Set  the	filesystem revision for the new filesystem.  Note that
	      1.2 kernels only support revision 0 filesystems.	The default is
	      to create revision 1 filesystems.

       -S     Write  superblock and group descriptors only.  This is useful if
	      all of the superblock and backup superblocks are corrupted,  and
	      a	 last-ditch  recovery  method is desired.  It causes mke2fs to
	      reinitialize the superblock and  group  descriptors,  while  not
	      touching	the  inode table and the block and inode bitmaps.  The
	      e2fsck program should be run immediately after  this  option  is
	      used,  and  there is no guarantee that any data will be salvage‐
	      able.  It is critical to specify the correct  filesystem	block‐
	      size when using this option, or there is no chance of recovery.

       -t fs-type
	      Specify  the filesystem type (i.e., ext2, ext3, ext4, etc.) that
	      is to be created.	 If this option is not specified, mke2fs  will
	      pick  a default either via how the command was run (for example,
	      using a name of the form mkfs.ext2, mkfs.ext3, etc.)  or	via  a
	      default  as  defined by the /etc/mke2fs.conf file.   This option
	      controls which filesystem options are used by default, based  on
	      the fstypes configuration stanza in /etc/mke2fs.conf.

	      If  the -O option is used to explicitly add or remove filesystem
	      options that should be set in the newly created filesystem,  the
	      resulting	 filesystem  may not be supported by the requested fs-
	      type.  (e.g., "mke2fs -t ext3 -O extent /dev/sdXX" will create a
	      filesystem  that	is not supported by the ext3 implementation as
	      found in the Linux kernel; and "mke2fs -t ext3  -O  ^has_journal
	      /dev/hdXX" will create a filesystem that does not have a journal
	      and hence will not be supported by the ext3 filesystem  code  in
	      the Linux kernel.)

       -T usage-type[,...]
	      Specify  how  the filesystem is going to be used, so that mke2fs
	      can choose optimal filesystem  parameters	 for  that  use.   The
	      usage  types that are supported are defined in the configuration
	      file /etc/mke2fs.conf.  The user may specify one or  more	 usage
	      types using a comma separated list.

	      If  this	option	is is not specified, mke2fs will pick a single
	      default usage type based on the size of  the  filesystem	to  be
	      created.	 If  the  filesystem  size  is less than or equal to 3
	      megabytes, mke2fs will use the filesystem type floppy.   If  the
	      filesystem  size is greater than 3 but less than or equal to 512
	      megabytes, mke2fs(8) will use the filesystem type small.	If the
	      filesystem size is greater than or equal to 4 terabytes but less
	      than 16 terabytes, mke2fs(8) will use the filesystem  type  big.
	      If the filesystem size is greater than or equal to 16 terabytes,
	      mke2fs(8)	 will  use  the	 filesystem  type  huge.    Otherwise,
	      mke2fs(8) will use the default filesystem type default.

       -U UUID
	      Create the filesystem with the specified UUID.

       -v     Verbose execution.

       -V     Print the version number of mke2fs and exit.

	      If set to non-zero integer value, its value is used to determine
	      how often sync(2) is called during inode table initialization.

	      Determines  the  location	 of  the   configuration   file	  (see

	      If set to non-zero integer value, its value is used to determine
	      first meta block group. This is mostly for debugging purposes.

	      If set to non-zero integer value, its value is used to determine
	      physical sector size of the device.

	      If  set,	do  not show the message of filesystem automatic check
	      caused by mount count or check interval.

       This  version  of  mke2fs   has	 been	written	  by   Theodore	  Ts'o

       mke2fs  accepts the -f option but currently ignores it because the sec‐
       ond extended file system does not support fragments yet.
       There may be other ones.	 Please, report them to the author.

       mke2fs  is  part	 of  the  e2fsprogs  package  and  is  available  from

       mke2fs.conf(5),	 badblocks(8),	 dumpe2fs(8),  e2fsck(8),  tune2fs(8),

E2fsprogs version 1.42.9	 December 2013			     MKE2FS(8)

List of man pages available for Archlinux

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net