mke2fs



MKE2FS(8)                                                            MKE2FS(8)




NAME

       mke2fs - create an ext2/ext3 filesystem


SYNOPSIS

       mke2fs [ -c | -l filename ] [ -b block-size ] [ -f fragment-size ] [ -g
       blocks-per-group ] [ -i bytes-per-inode ] [ -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 filesystem-type ] [ -V ] device [  blocks-count
       ]

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


DESCRIPTION

       mke2fs is used to create an ext2/ext3 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 speci-
       fied.


OPTIONS

       -b block-size
              Specify the size of blocks in bytes.  Valid block size vales are
              1024, 2048 and 4096 bytes per block.  If omitted, mke2fs  block-
              size is heuristically determined by the file system 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 cer-
              tain hardware devices which require that the blocksize be a mul-
              tiple 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:

                   stride=stripe-size
                          Configure  the  filesystem  for  a  RAID  array with
                          stripe-size filesystem blocks per stripe.

                   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.

       -f fragment-size
              Specify the size of fragments in bytes.

       -F     Force mke2fs to run, even if the specified device is not a block
              special device, or appears to be mounted.

       -g blocks-per-group
              Specify  the number of blocks in a block group.  There is gener-
              ally no reason 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 -R option rather than
              manipulating the number of blocks per group.)   This  option  is
              generally used by developers who are developing test cases.

       -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  then  too many inodes will be made.  Be
              warned that is not possible to expand the number of inodes on  a
              filesystem  after it is created, so be careful deciding the cor-
              rect value for this parameter.

       -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  102,400
                          filesystem blocks.

                   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.

                          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
                          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 auto-
              matically  pass the correct parameters to the badblocks program.

       -L     Set the volume label for the filesystem.

       -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     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
              Manually override the default value of the "creator os" field of
              the filesystem.  Normally the creator field is set by default to
              the native OS of the mke2fs executable.

       -O feature[,...]
              Create  filesystem  with  given  features  (filesystem options),
              overriding  the  default  filesystem  options.   Currently,  the
              sparse_super and filetype features are turned on by default when
              mke2fs is run on a system with Linux 2.2 or later  (unless  cre-
              ator-os  is  set  to the Hurd).  Filesystems that may need to be
              mounted on pre-2.2 Linux or other kernels should be created with
              -O  none  (or  -r 0 for Linux 1.2) which will disable these fea-
              tures, even if mke2fs is run on a system which can support them.

              The following filesystem options are supported:

                   dir_index
                          Use  hashed  b-trees  to  speed  up lookups in large
                          directories.

                   filetype
                          Store file type information in directory entries.

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

                   journal_dev
                          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.

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

       -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 how the filesystem is going to be used, so  that  mke2fs
              can  chose optimal filesystem parameters for that use.  The sup-
              ported filesystem types are:

                   news        one inode per 4kb block

                   largefile   one inode per megabyte

                   largefile4  one inode per 4 megabytes

       -v     Verbose execution.

       -V     Print the version number of mke2fs and exit.


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 sec-
       ond 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

       badblocks(8), dumpe2fs(8), e2fsck(8), tune2fs(8)



E2fsprogs version 1.38             June 2005                         MKE2FS(8)

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