Provided by: e2fsprogs_1.42.13-1ubuntu1.2_amd64 bug

NAME

       mke2fs - create an ext2/ext3/ext4 filesystem

SYNOPSIS

       mke2fs  [  -c  | -l filename ] [ -b block-size ] [ -D ] [ -f fragment-size ] [ -g blocks-per-group ] [ -G
       number-of-groups ] [ -i bytes-per-inode ] [ -I inode-size ] [ -j ] [ -J journal-options ] [ -N number-of-
       inodes  ] [ -n ] [ -m reserved-blocks-percentage ] [ -o creator-os ] [ -O [^]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 [ fs-size ]

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

DESCRIPTION

       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.

OPTIONS

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

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

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

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

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

                   mmp_update_interval=interval
                          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.

                   stride=stride-size
                          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 allocator.

                   stripe_width=stripe-width
                          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 written.

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

                   resize=max-online-resize
                          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.

                   num_backup_sb=<0|1|2>
                          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.

                   root_owner[=uid:gid]
                          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 filesystem to change based on the user running mke2fs.

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

                   discard
                          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.

                   nodiscard
                          Do not attempt to discard blocks at mkfs time.

                   quotatype
                          Specify which quota type ('usr' or 'grp') is to be initialized. This option has effect
                          only  if  the quota feature is set. Without this extended option, the default behavior
                          is to initialize both user and group quotas.

       -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.

              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
              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  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 maintain 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 negatively 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:

                   size=journal-size
                          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)

                   location=journal-location
                          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.

                   device=external-journal
                          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 tune2fs(8).

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

       -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 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 mounted.

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

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

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

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

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

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

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

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

              If this option is is not specified, mke2fs will pick a single default usage type based on the size
              of the filesystem to be created.  If the filesystem size is less than 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
              Create the filesystem with the specified UUID.

       -v     Verbose execution.

       -V     Print the version number of mke2fs and exit.

ENVIRONMENT

       MKE2FS_SYNC
              If set to non-zero integer value, its value is used to  determine  how  often  sync(2)  is  called
              during inode table initialization.

       MKE2FS_CONFIG
              Determines the location of the configuration file (see mke2fs.conf(5)).

       MKE2FS_FIRST_META_BG
              If  set  to non-zero integer value, its value is used to determine first meta block group. This is
              mostly for debugging purposes.

       MKE2FS_DEVICE_SECTSIZE
              If set to non-zero integer value, its value is used to  determine  physical  sector  size  of  the
              device.

       MKE2FS_SKIP_CHECK_MSG
              If  set,  do  not  show  the  message of filesystem automatic check caused by mount count or check
              interval.

AUTHOR

       This version of mke2fs has been written by Theodore Ts'o <tytso@mit.edu>.

BUGS

       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.

AVAILABILITY

       mke2fs is part of the e2fsprogs package and is available from http://e2fsprogs.sourceforge.net.

SEE ALSO

       mke2fs.conf(5), badblocks(8), dumpe2fs(8), e2fsck(8), tune2fs(8), ext4(5)