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       mke2fs - create an ext2/ext3/ext4 filesystem


       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 ] [ -K ] [ -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 ] 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  negative, 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
              compatibility.   The following extended options are supported:

                          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

                          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

                          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

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

       -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
              create  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
              generally 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
              performance 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
              performance.   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
              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  102,400
                          filesystem blocks.

                          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
                          multiple 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,
                          external-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

       -K     Keep, do not attempt to discard blocks at mkfs time  (discarding
              blocks  initially  is useful on solid state devices and sparse /
              thin-provisioned storage).

       -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
              automatically  pass  the  correct  parameters  to  the badblocks

       -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
              features that are  enabled  by  default  are  specified  by  the
              base_features  relation, either in the [defaults] section in the
              /etc/mke2fs.conf  configuration  file,  or  in  the   [fs_types]
              subsections  for  the usage types as specified by the -T option,
              further  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]
              section 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
              configuration file.

              The filesystem feature set is comprised of a list  of  features,
              separated  by  commas,  that  are  to  be enabled.  To disable a
              feature, simply prefix the feature  name  with  a   caret  ('^')
              character.   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
                          storing the location of data blocks in an inode, use
                          extents  instead.   This  is  a  much more efficient
                          encoding  which   speeds   up   filesystem   access,
                          especially for large files.

                          Store file type information in directory entries.

                          Allow   the  per-block  group  metadata  (allocation
                          bitmaps 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).

                          Create an external ext3 journal on the given  device
                          instead  of  a  regular  ext2 filesystem.  Note that
                          external-journal must be created with the same block
                          size as the filesystems that will be using it.

                          Filesystem  can  contain files that are greater than
                          2GB.  (Modern kernels set this feature automatically
                          when a file > 2GB is created.)

                          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
                          blockgroup.  This feature can  speed  up  filesystem
                          creation  time  noticeably  (if  lazy_itable_init is
                          enabled),  and   can   also   reduce   e2fsck   time
                          dramatically.   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
              salvageable.   It  is critical to specify the correct filesystem
              blocksize when using this option,  or  there  is  no  chance  of

       -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

              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 extents /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(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 small.  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.


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


       mke2fs  accepts  the  -f  option  but  currently ignores it because the
       second 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)