Provided by: e2fsprogs_1.46.5-2ubuntu2_amd64 bug


       mke2fs - create an ext2/ext3/ext4 file system


       mke2fs  [ -c | -l filename ] [ -b block-size ] [ -C cluster-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 file system, 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 file system, 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  powers  of  two
              from  1024  up  to  65536  (however note that the kernel is able to mount only file
              systems with block-size smaller or equal to the  system  page  size  -  4k  on  x86
              systems,  up  to  64k  on  ppc64 or aarch64 depending on kernel configuration).  If
              omitted, block-size is heuristically determined by the file  system  size  and  the
              expected  usage  of the file system (see the -T option).  In most common cases, the
              default block size is 4k. 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

       -C  cluster-size
              Specify  the  size of cluster in bytes for file systems 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 file

       -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
              file system error will cause e2fsck(8) to check the file system on the  next  boot.
              error-behavior can be one of the following:

                   continue    Continue normal execution.

                   remount-ro  Remount file system read-only.

                   panic       Cause a kernel panic.

       -E extended-options
              Set  extended  options  for the file system.  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, but is deprecated.  The following extended options are supported:

                          Enable the casefold feature in the super block and set encoding-name as
                          the  encoding  to  be  used.   If  encoding-name  is not specified, the
                          encoding defined in mke2fs.conf(5) is used.

                          Define parameters for file name character encoding  operations.   If  a
                          flag  is  not  changed using this parameter, its default value is used.
                          encoding-flags should  be  a  comma-separated  lists  of  flags  to  be
                          enabled.  To disable a flag, add it to the list with the prefix "no".

                          The  only  flag  that  can  be set right now is strict which means that
                          invalid strings should be rejected by the file system.  In the  default
                          configuration, the strict flag is disabled.

                          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 file system for a RAID array with stride-size file system
                          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  file system 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 allocator.

                          Configure  the  file  system  for  a  RAID array with stripe-width file
                          system 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 written.

                          Create the file system at an offset from the beginning of the device or
                          file.   This  can  be  useful  when  creating  disk  images for virtual

                          Reserve enough space so that the block group descriptor table can  grow
                          to support a file system 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  file  system
                          initialization  noticeably,  but  it  requires  the  kernel  to  finish
                          initializing the file system in the background when the file system  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 file system 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.

                          Normally mke2fs will copy the extended attributes of the files  in  the
                          directory  hierarchy specified via the (optional) -d option.  This will
                          disable the copy and leaves the files in the newly created file  system
                          without any extended attributes.

                          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
                          maximizes 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
                          directory 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  file system to change based on the user
                          running mke2fs.

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

                          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 file system 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  file  system,  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 file system even if the file system appears to be
              in use or is mounted (a truly dangerous thing to do), this option must be specified

       -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 file system.
              (For  administrators who are creating file systems 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  file  system.   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  file  system
              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 file system, 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 file system
              after it is created, so be careful deciding the correct value for  this  parameter.
              Note  that  resizing  a  file  system changes the number of inodes to maintain this

       -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 file  system  and  can  also
              negatively  impact  performance.  It is not possible to change this value after the
              file system is created.

              File systems with an inode size of 128  bytes  do  not  support  timestamps  beyond
              January  19,  2038.   Inodes  which  are  256 bytes or larger will support extended
              timestamps, project id's, and the ability to store some extended attributes in  the
              inode table for improved performance.

              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

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

                          Create an additional fast commit journal area of size  fast-commit-size
                          kilobytes.  This option is only valid if fast_commit feature is enabled
                          on the file system. If this option is not specified and if  fast_commit
                          feature  is turned on, fast commit area size defaults to journal-size /
                          64 megabytes. The total size of the journal  with  fast_commit  feature
                          set  is  journal-size + ( fast-commit-size * 1024) megabytes. The total
                          journal size may be no more than 10,240,000 file system 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 file system to the journal block device located on external-
                          journal.  The external journal must already have been created using the

                          mke2fs -O journal_dev external-journal

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

                          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 file system.

       -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 program.

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

       -m reserved-blocks-percentage
              Specify the percentage of the file system 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 file system.  The default percentage is 5%.

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

       -n     Causes mke2fs to not actually create a file system, but display what it would do if
              it were to create a file system.  This can be used to determine the location of the
              backup  superblocks  for a particular file system, so long as the mke2fs parameters
              that were passed when the file system 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 file system (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 file
              system.  The creator field is set by default to the  name  of  the  OS  the  mke2fs
              executable was compiled for.

       -O [^]feature[,...]
              Create  a file system with the given features (file system options), overriding the
              default file system  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 file system and usage types.   See  the
              mke2fs.conf(5)  manual  page  for  more  details.   The  file  system type-specific
              configuration setting found in the [fs_types]  section  will  override  the  global
              default found in [defaults].

              The  file  system  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  file system type being created, or in the [defaults] section of
              the configuration file.

              The file system 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.  Features with dependencies will not be  removed
              successfully.   The  pseudo-file  system  feature "none" will clear all file system

       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 file system revision for the new file system.  Note that 1.2  kernels  only
              support revision 0 file systems.  The default is to create revision 1 file systems.

       -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
              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.  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  file  system  will  be  further
              corrupted.  In some cases, such as file systems that have been resized, or have had
              features enabled after format time, it  is  impossible  to  overwrite  all  of  the
              superblocks  correctly, and at least some file system corruption will occur.  It is
              best to run this on a full copy of the file system so other options can be tried if
              this doesn't work.

       -t fs-type
              Specify  the file system 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  file  system 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  file  system  options  that
              should  be  set in the newly created file system, the resulting file system may not
              be supported by the requested fs-type.  (e.g., "mke2fs -t ext3 -O extent /dev/sdXX"
              will create a file system 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
              file  system  that  does  not have a journal and hence will not be supported by the
              ext3 file system code in the Linux kernel.)

       -T usage-type[,...]
              Specify how the file system is going to be used, so that mke2fs can choose  optimal
              file  system  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 file system to be created.  If the  file  system  size  is
              less  than  3  megabytes, mke2fs will use the file system type floppy.  If the file
              system size is greater than or equal to 3 but less than  512  megabytes,  mke2fs(8)
              will  use  the  file system type small.  If the file system size is greater than or
              equal to 4 terabytes but less than 16 terabytes, mke2fs(8) will use the file system
              type  big.   If  the  file  system  size  is greater than or equal to 16 terabytes,
              mke2fs(8) will use the file system type huge.  Otherwise, mke2fs(8)  will  use  the
              default file system type default.

       -U UUID
              Set  the  universally  unique  identifier  (UUID)  of the file system to UUID.  The
              format of the UUID is a series of hex  digits  separated  by  hyphens,  like  this:
              "c1b9d5a2-f162-11cf-9ece-0020afc76f16".   The UUID parameter may also be one of the

                   clear  clear the file system 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 directive 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 mke2fs.conf(5)).

              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 logical sector
              size of the device.

              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 file system 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), ext4(5)