MKFS.EXT3 linux command manual

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-percent-
       age ] [ -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  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 spec-
       ified.

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 hueristically 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 hueristics to
              determine the appropriate block size, with the constraint  that
              the block size will be at least block-size bytes.  This is use-
              ful for certain hardware devices which require that the  block-
              size be a multiple of 2k.

       -c     Check  the  device for bad blocks before creating the file sys-
              tem.  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 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 filesys-
                          tem 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,
                          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  vol-
                          ume  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  check-
              ing  a disk for bad blocks before formatting it, as mke2fs will
              automatically pass the correct parameters to the badblocks pro-
              gram.

       -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 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).
              Features which are normally turned on by default  may  be  dis-
              abled by prefixing the feature with a caret ('^') symbol.  Cur-
              rently, 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 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  features,  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.

       -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
              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
       .

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 1.35          February 2004                       MKE2FS(8)