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       mkfs.ocfs2 - Creates an OCFS2 file system.


       mkfs.ocfs2  [-b  block-size]  [-C  cluster-size]  [-L volume-label] [-M
       mount-type]     [-N     number-of-nodes]      [-J      journal-options]
       [--fs-features=[no]sparse...]   [--fs-feature-level=feature-level]  [-T
       filesystem-type] [-FqvV] device [blocks-count]


       mkfs.ocfs2 is used to create an OCFS2 file system on a device,  usually
       a partition on a shared disk. In order to prevent data loss, mkfs.ocfs2
       will not format an existing OCFS2 volume  if  it  detects  that  it  is
       mounted  on another node in the cluster. This tool requires the cluster
       service to be online.


       -b, --block-size block-size
              Valid block size values are 512, 1K, 2K and 4K bytes per  block.
              If  omitted,  a  value will be heuristically determined based on
              the expected usage of the file system (see  the  -T  option).  A
              block  size  of 512 bytes is never recommended. Choose 1K, 2K or

       -C, --cluster-size cluster-size
              Valid cluster size values are 4K, 8K, 16K, 32K, 64K, 128K, 256K,
              512K   and  1M.  If  omitted,  a  value  will  be  heuristically
              determined based on the expected usage of the file  system  (see
              the  -T option). For volumes expected to store large files, like
              database files,  while  a  cluster  size  of  128K  or  more  is
              recommended,  one  can  opt  for  a smaller size as long as that
              value is not smaller than the database block size.  For  others,
              use 4K.

       -F, --force
              For existing OCFS2 volumes, mkfs.ocfs2 ensures the volume is not
              mounted on any node in the cluster before formatting.  For  that
              to  work,  mkfs.ocfs2  expects the cluster service to be online.
              Specify this option to disable this check.

       -J, --journal-options options
              Create the journal using options specified on the  command-line.
              Journal  options  are  comma separated, and may take an argument
              using  the  equals  (’=’)  sign.  The  following   options   are

                          Create  a journal of size journal-size. Minimum size
                          is  4M.   If  omitted,  a  value  is   heuristically
                          determined based upon the file system size.

                          Use  a  standard 32bit journal.  The journal will be
                          able to access up to 2^32-1  blocks.   This  is  the
                          default.   It  has been the journal format for OCFS2
                          volumes  since  the  beginning.   The   journal   is
                          compatible  with  all versions of OCFS2.  Prepending
                          no is equivalent to the block64 journal option.

                          Use a 64bit journal.  The journal will  be  able  to
                          access  up  to  2^64-1  blocks.   This  allows large
                          filesystems  that  can  extend  to  the  theoretical
                          limits   of   OCFS2.    It   requires  a  new-enough
                          filesystem driver that uses the new journalled block
                          device,  JBD2.  Prepending  no  is equivalent to the
                          block32 journal option.

       -L, --label volume-label
              Set the volume label for the file system.  This  is  useful  for
              mounting-by-label. Limit the label to under 64 bytes.

       -M, --mount mount-type
              Valid  types  are local and cluster. Local mount allows users to
              mount the volume without the cluster  overhead  and  works  only
              with  OCFS2 bundled with Linux kernels 2.6.20 or later. Defaults
              to cluster.

       -N, --node-slots number-of-node-slots
              Valid number ranges from 1 to 255.  This  number  specifies  the
              maximum   number  of  nodes  that  can  concurrently  mount  the
              partition. If omitted, the number defaults to 8. The  number  of
              slots can be later tuned up or down using tunefs.ocfs2.

       -T filesystem-type
              Specify  how  the  filesystem  is  going  to  be  used,  so that
              mkfs.ocfs2 can chose optimal filesystem parameters for that use.
              The supported filesystem types are:

                   mail   Appropriate  for  file  systems which will have many
                          meta data updates. Creates a larger journal.

                          Appropriate for  file  systems  which  will  host  a
                          relatively small number of very large files. A small
                          journal is selected. Cluster size will be  at  least

              Turn  specific file system features on or off. A comma separated
              list of feature flags can be provided, and mkfs.ocfs2  will  try
              to  create  the file system with those features set according to
              the list. To turn a feature on, include it in the list. To  turn
              a  feature  off,  prepend  no  to  the  name.  Choices here will
              override individual  features  set  via  the  --fs-feature-level
              option. Refer to the section titled feature compatibility before
              selecting specific features. The following flags are supported:

                          mkfs.ocfs2, by default, makes up to 6 backup  copies
                          of the super block at offsets 1G, 4G, 16G, 64G, 256G
                          and 1T depending on the size of  the  volume.   This
                          can  be useful in disaster recovery. This feature is
                          fully compatible  with  all  versions  of  the  file
                          system and generally should not be disabled.

                   local  Create  the file system as a local mount, so that it
                          can be mounted without a cluster stack.

                   sparse Enable support for sparse files.  With  this,  OCFS2
                          can  avoid  allocating  (and  zeroing)  data to fill
                          holes. Turn this feature on if  you  can,  otherwise
                          extends and some writes might be less performant.

                          Enable  unwritten  extents support. With this turned
                          on, an application  can  request  that  a  range  of
                          clusters  be pre-allocated within a file. OCFS2 will
                          mark those extents  with  a  special  flag  so  that
                          expensive data zeroing doesn’t have to be performed.
                          Reads and writes to a pre-allocated  region  act  as
                          reads  and writes to a hole, except a write will not
                          fail due to lack of data  allocation.  This  feature
                          requires sparse file support to be turned on.

                          Enable  inline-data  support.  If  this  feature  is
                          turned  on,  OCFS2  will  store  small   files   and
                          directories   inside   the   inode  block.  Data  is
                          transparently moved out to  an  extent  when  it  no
                          longer  fits  inside the inode block. In some cases,
                          this can also make a positive impact  on  cold-cache
                          directory and file operations.

                          The  slot-map  is a hidden file on an OCFS2 fs which
                          is  used  to  map  mounted  nodes  to  system   file
                          resources.  The  extended  slot  map allows a larger
                          range of possible node numbers, which is useful  for
                          userspace    cluster   stacks.   This   feature   is
                          automatically turned on when needed, thus users have
                          no need to turn this on manually.

                   xattr  Enable   extended   attributes  support.  With  this
                          enabled,  users  can  attach  name:value  pairs   to
                          objects  within the file system. In OCFS2, the names
                          can be upto 255 bytes in length, terminated  by  the
                          first  NUL byte. While it is not required, printable
                          names (ASCII) are recommended.  The  values  can  be
                          upto  64KB  of arbitrary binary data. Attributes can
                          be attached to all types of inodes:  regular  files,
                          directories, symbolic links, device nodes, etc. This
                          feature  is  required  for  users  wanting  to   use
                          extended  security  facilities  like  POSIX  ACLs or

              Choose from a set of pre-determined file-system  features.  This
              option  is  designed to allow users to conveniently choose a set
              of file system features which fits  their  needs.  There  is  no
              downside to trying a set of features which your module might not
              support - if it won’t mount the new file system simply  reformat
              at  a  lower  level.  Feature  levels  can be fine-tuned via the
              --fs-features option. Currently, there are 3  types  of  feature

                          Chooses  fewer  features  but  ensures that the file
                          system can be mounted from  older  versions  of  the
                          OCFS2 module.

                          The  default  feature  set tries to strike a balance
                          between  providing  new  features  and   maintaining
                          compatibility  with  relatively  recent  versions of
                          OCFS2. It currently enables  sparse,  unwritten  and

                          Choose  the  maximum  amount  of features available.
                          This will typically  provide  the  best  performance
                          from  OCFS2 at the expense of creating a file system
                          that is only compatible with very recent versions of
                          the OCFS2 kernel module.

              This  option  is  deprecated, please use --fs-features=nobackup-
              super instead.

       -q, --quiet
              Quiet mode.

       -v, --verbose
              Verbose mode.

       -V, --version
              Print version and exit.

              Usually mkfs.ocfs2 automatically  determines  the  size  of  the
              given  device  and  creates  a  file system that uses all of the
              available space on the device.  This optional argument specifies
              that  the  file  system  should only consume the given number of
              file system blocks (see -b) on the device.


       This section lists the file system features that have been added to the
       OCFS2  file  system  and  the  version that each appeared in. The table
       below lists the versions of the mainline Linux kernel and that  of  the
       file  system  for  the Enterprise Linux Distributions. Users should use
       this information to enable only those features that  are  available  in
       the file system that they are using.

       |Feature          | Mainline Kernel Version | Enterprise OCFS2 Version |
       |block64          |      Linux 2.6.29       |   Not available as yet   |
       |local            |      Linux 2.6.20       |    OCFS2 1.2 and 1.4     |
       |sparse           |      Linux 2.6.22       |        OCFS2 1.4         |
       |unwritten        |      Linux 2.6.23       |        OCFS2 1.4         |
       |inline-data      |      Linux 2.6.24       |        OCFS2 1.4         |
       |extended-slotmap |      Linux 2.6.27       |   Not available as yet   |
       |xattr            |      Linux 2.6.29       |   Not available as yet   |

       Users can query the features enabled in the file system as follows:

       [root@node ~]# tunefs.ocfs2 -Q "Label: %V\nFeatures: %H %O\n" /dev/sdg1
       Label: apache_files_10
       Features: sparse inline-data unwritten


       debugfs.ocfs2(8)    fsck.ocfs2(8)    tunefs.ocfs2(8)   mounted.ocfs2(8)
       ocfs2console(8) o2cb(7)


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