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MKE2FS(8)		    System Manager's Manual		     MKE2FS(8)

       mke2fs - create an ext2/ext3/ext4 filesystem

       mke2fs  [  -c | -l filename ] [ -b block-size ] [ -d root-directory ] [
       -D ] [ -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  [^]feature[,...]   ] [ -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 ] [ -e
       errors-behavior ] [ -z undo_file ] device [ fs-size ]

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

       mke2fs  is used to create an ext2, ext3, or ext4 filesystem, usually in
       a disk partition (or file) named by device.

       The file system size is specified by fs-size.  If fs-size does not have
       a  suffix,  it  is interpreted as power-of-two kilobytes, unless the -b
       blocksize option is specified, in which case fs-size is interpreted  as
       the  number  of	blocksize blocks.   If the fs-size is suffixed by 'k',
       'm', 'g', 't' (either upper-case or lower-case), then it is interpreted
       in  power-of-two	 kilobytes,  megabytes, gigabytes, terabytes, etc.  If
       fs-size is omitted, mke2fs will create the file	system	based  on  the
       device size.

       If mke2fs is run as mkfs.XXX (i.e., mkfs.ext2, mkfs.ext3, or mkfs.ext4)
       the option -t XXX is implied; so mkfs.ext3 will create  a  file	system
       for  use	 with  ext3,  mkfs.ext4 will create a file system for use with
       ext4, and so on.

       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 root-directory
	      Copy the contents of the given directory into the root directory
	      of the filesystem.

       -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 error-behavior
	      Change the behavior of the kernel code when errors are detected.
	      In all cases, a filesystem error will cause e2fsck(8)  to	 check
	      the  filesystem  on the next boot.  error-behavior can be one of
	      the following:

		   continue    Continue normal execution.

		   remount-ro  Remount filesystem read-only.

		   panic       Cause a kernel panic.

       -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-

			  Create  the  filesystem at an offset from the begin-
			  ning of the device or file.  This can be useful when
			  creating disk images for virtual machines.

			  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.

			  If  the sparse_super2 file system feature is enabled
			  this option controls whether there will be 0, 1,  or
			  2 backup superblocks created in the file system.

		   packed_meta_blocks[= <0 to disable, 1 to enable>]
			  Place	 the allocation bitmaps and the inode table at
			  the beginning of the	disk.	This  option  requires
			  that	the  flex_bg file system feature to be enabled
			  in order for it to have effect, and will also create
			  the  journal	at  the	 beginning of the file system.
			  This option is useful for flash devices that use SLC
			  flash	 at  the beginning of the disk.	 It also maxi-
			  mizes the range of contiguous data blocks, which can
			  be useful for certain specialized use cases, such as
			  supported Shingled Drives.

			  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.

			  Specify the which  quota types (usrquota,  grpquota,
			  prjquota)  which  should  be	enabled in the created
			  file system.	The argument of this  extended	option
			  should  be  a colon separated list.  This option has
			  effect only if  the  quota  feature  is  set.	   The
			  default quota types to be initialized if this option
			  is not specified is both user and group quotas.   If
			  the  project	feature is enabled that project quotas
			  will be initialized as well.

       -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)

			  Specify  the	location of the journal.  The argument
			  journal-location can either be specified as a	 block
			  number,  or  if the number has a units suffix (e.g.,
			  'M', 'G', etc.) interpret it as the offset from  the
			  beginning of the file system.

			  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 ('^') charac-
	      ter.  Features with dependencies will not	 be  removed  success-
	      fully.   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 an extreme
	      measure  to  be taken only in the very unlikely case that all of
	      the superblock and backup superblocks are corrupted, and a last-
	      ditch  recovery  method  is  desired  by	experienced users.  It
	      causes mke2fs to reinitialize the superblock and group  descrip-
	      tors, 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 salvageable.   Due  to  the  wide	 variety  of  possible
	      options to mke2fs that affect the on-disk layout, it is critical
	      to specify exactly the same format options, such	as  blocksize,
	      fs-type,	feature	 flags,	 and  other  tunables  when using this
	      option, or the filesystem will be further	 corrupted.   In  some
	      cases,  such  as filesystems that have been resized, or have had
	      features enabled after format time, it is	 impossible  to	 over-
	      write  all  of  the  superblocks	correctly,  and	 at least some
	      filesystem corruption will occur.	 It is best to run this	 on  a
	      full  copy  of  the  filesystem so other options can be tried if
	      this doesn't work.

       -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	 3  megabytes,
	      mke2fs  will  use the filesystem type floppy.  If the filesystem
	      size is greater than or equal to 3 but less than 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
	      Set the universally unique identifier (UUID) of  the  filesystem
	      to UUID.	The format of the UUID is a series of hex digits sepa-
	      rated	     by		 hyphens,	   like		 this:
	      "c1b9d5a2-f162-11cf-9ece-0020afc76f16".	The UUID parameter may
	      also be one of the following:

		   clear  clear the filesystem UUID

		   random generate a new randomly-generated UUID

		   time	  generate a new time-based UUID

       -v     Verbose execution.

       -V     Print the version number of mke2fs and exit.

       -z undo_file
	      Before overwriting a file system block, write the	 old  contents
	      of  the  block to an undo file.  This undo file can be used with
	      e2undo(8) to restore the old contents of the file system	should
	      something	 go  wrong.   If  the  empty  string  is passed as the
	      undo_file argument, the undo file will  be  written  to  a  file
	      named  mke2fs-device.e2undo  in  the directory specified via the
	      E2FSPROGS_UNDO_DIR environment variable or the  undo_dir	direc-
	      tive in the configuration file.

	      WARNING: The undo file cannot be used to recover from a power or
	      system crash.

	      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  is  part	 of  the  e2fsprogs  package  and  is  available  from

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

E2fsprogs version 1.43.5	  August 2017			     MKE2FS(8)