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mke2fs(8) - mke2fs - create an ext2/ext3 filesystem - man 8 mke2fs

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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 ] [ -R
       raid-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(1,8)  a  disk
       partition).   device  is  the  special file(1,n) 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(1,n) system size.  If
       called as mkfs.ext3 a journal is created as if(3,n) the -j option was speci-
       fied.

OPTIONS
       -b block-size
              Specify the size of blocks in(1,8) bytes.  Valid block size vales are
              1024, 2048 and 4096 bytes per block.  If omitted, mke2fs  block-
              size is hueristically determined by the file(1,n) system size and the
              expected usage of the filesystem (see the -T option).  If block-
              size  is  negative, then mke2fs will use hueristics 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(1,n) system.
              If this option is specified twice, then a  slower,  destructive,
              read-write test is used instead of a fast read-only test.

       -f fragment-size
              Specify the size of fragments in(1,8) bytes.

       -F     Force mke2fs to run, even if(3,n) the specified device is not a block
              special device, or appears to be mounted.

       -g blocks-per-group
              Specify the number of blocks in(1,8) a block group.  There is  gener-
              ally  no  reason  the  user  to  ever set(7,n,1 builtins) 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(1,8) 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(3,n) using 1k blocks, 4MB  if(3,n)  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(1,8)
                          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(1,8) 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(1,3) 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 value defaults to 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  filesytem  should  be
              mounted.

       -n     causes  mke2fs  to not actually create a filesystem, but display
              what it would do if(3,n) 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(7,n,1 builtins) by default to
              the native OS of the mke2fs executable.

       -O feature[,...]
              Create  filesystem  with  given  features  (filesystem options).
              Features which are normally turned on by default may be disabled
              by  prefixing the feature with a caret ('^') symbol.  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
              creator-os is set(7,n,1 builtins) 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(3,n) 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(1,8)  large
                          directories.

                   filetype
                          Store file(1,n) type information in(1,8) directory entries.

                   has_journal
                          Create  an ext3 journal (as if(3,n) 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(3,n) mke2fs is run in(1,8) 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.

       -R raid-options
              Set raid-related options for the filesystem.  Raid  options  are
              comma separated, and may take an argument using the equals ('=')
              sign.  The following options are supported:

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

       -S     Write  superblock and group descriptors only.  This is useful if(3,n)
              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(1,3,5) number of mke2fs and exit.

AUTHOR
       This  version(1,3,5)  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(1,n) 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(1,3,5) 1.35           February 2004                       MKE2FS(8)

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