mke2fs [ -c | -l filename ] [ -b block-size ] [ -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.

       -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.   The following extended options are supported:

                          Adjust  the  initial MMP update interval to interval
                          seconds.  Specifying an interval of 0 means  to  use
                          the  default  interval.  The specified interval must

                          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.

                          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.

              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.

       -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
              expand the number of inodes on a filesystem after it is created,
              so be careful deciding the correct value for this parameter.

       -I inode-size
              Specify  the  size  of  each  inode  in  bytes.   mke2fs creates
              256-byte inodes by default.  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 perfor-
              mance.   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  negatively  impact  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.   It is not possible to change this value
              after the filesystem is created.

       -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
                          (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
       -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.   The  pseudo-filesystem  feature  "none"  will  clear  all
              filesystem features.

                          Use hashed b-trees to  speed  up  lookups  in  large

                   extent Instead of using the indirect block scheme for stor-
                          ing the location of data blocks  in  an  inode,  use
                          extents  instead.   This  is  a  much more efficient
                          encoding which speeds up  filesystem  access,  espe-
                          cially for large files.

                          Store file type information in directory entries.

                          Allow  the per-block group metadata (allocation bit-
                          maps and inode tables) to be placed anywhere on  the
                          storage  media.   In addition, mke2fs will place the
                          per-block group metadata together  starting  at  the
                          first  block  group  of  each "flex_bg group".   The
                          size of the flex_bg group can be specified using the
                          -G option.

                          Create an ext3 journal (as if using the -j option).

                   quota  Create quota inodes  (inode#  3  for  userquota  and
                          inode#  4  for  group  quota)  and  set  them in the
                          superblock.  With this feature, the quotas  will  be
                          enabled   automatically   when   the  filesystem  is

                          Reserve space so the block  group  descriptor  table
                          may  grow in the future.  Useful for online resizing
                          using resize2fs.  By default mke2fs will attempt  to
                          reserve enough space so that the filesystem may grow
                          to 1024 times its initial size.  This can be changed
                          using the resize extended option.

                          Create  a  filesystem  with  fewer superblock backup
                          copies (saves space on large filesystems).

                          Create a filesystem without initializing all of  the
                          block  groups.   This feature also enables checksums
                          and highest-inode-used  statistics  in  each  block-
                          group.   This  feature  can speed up filesystem cre-
                          ation  time  noticeably  (if   lazy_itable_init   is
                          enabled),  and  can also reduce e2fsck time dramati-
                          cally.  It is only supported by the ext4  filesystem
                          in recent Linux kernels.

       -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(5)  file.   This
              option controls which filesystem options are  used  by  default,
              based     on     the    fstypes    configuration    stanza    in
              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(5).   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.
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