mkfs.gfs2

mkfs.gfs2(8) System Manager's Manual mkfs.gfs2(8)

NAME

   mkfs.gfs2 - create a gfs2 filesystem

SYNOPSIS

   mkfs.gfs2 [options] device [block-count]

DESCRIPTION

   mkfs.gfs2 is used to create a gfs2 file system.

OPTIONS

   The  default values of the following options have been chosen for best results.  In most cases, there should be no need to choose different values. The exceptions to this are the num‐
   ber of journals (-j) and the lock table (-t), as these options will be specific to your cluster.

   -b bytes
          Set the filesystem block size to bytes which must be a power of two. The minimum block size is 512 and the block size cannot exceed the machine's memory  page  size,  which  on
          most architectures is 4096 bytes.  The default block size is 4096 bytes.

   -c megabytes
          Initial size of each journal's quota change file. The default is 1MB.

   -D     Enable debugging output.

   -h     Print out a help message describing the available options, then exit.

   -J megabytes
          The  size  of each journal. The minimum size is 8 megabytes and the maximum is 1024. If this is not specified, a value based on a sensible proportion of the file system will be
          chosen.

   -j journals
          The number of journals for mkfs.gfs2 to create.  At least one journal is required for each machine that will mount the filesystem concurrently.  If this option  is  not  speci‐
          fied,  only  one  journal  will  be created. This number may be used as an indicator of the number of nodes in the cluster in order to optimize the layout of the filesystem. As
          such, it is best to set this option with the maximum number of mounters in mind than to add more journals later.

   -K     Do not attempt to discard the block device contents. Issuing discards to the device allows some solid state devices and sparse or thin-provisioned storage devices  to  optimise
          free space. Other devices may emulate this behaviour by zeroing the device contents, which can be a slow process.

   -O     Override. This option prevents mkfs.gfs2 from asking for confirmation before writing the filesystem.

   -o     Specify extended options. Multiple options can be separated by commas. Valid extended options are:

             help   Display an extended options help summary, then exit.

             sunit=bytes
                    This  is  used to specify the stripe unit for a RAID device or striped logical volume.  This option ensures that resource groups will be stripe unit aligned and over‐
                    rides the stripe unit value obtained by probing the device. This value must be a multiple of the file system block size and must be specified with the swidth option.

             swidth=bytes
                    This is used to specify the stripe width for a RAID device or striped logical volume.  This option ensures that resource groups will be stripe aligned  and  overrides
                    the stripe width value obtained by probing the device. This value must be a multiple of the sunit option and must also be specified with it.

             align=[0|1]
                    Disable or enable the alignment of resource groups. The default behaviour is to align resource groups to the stripe width and stripe unit values obtained from probing
                    the device or specified with the swidth and sunit extended options.

             format=<number>
                    Set the filesystem format version. Testing only.

   -p protocol
          Specify the locking protocol to use when no locking protocol is specified at mount time. Valid locking protocols are:

             lock_dlm
                    This is the default. It enables DLM-based locking for use in shared storage configurations.

             lock_nolock
                    This enables single-node locking

   -q     Quiet mode. Do not print anything.

   -r megabytes
          mkfs.gfs2  will try to make resource groups approximately this large.  The minimum resource group size is 32 MB and the maximum is 2048 MB.  A large resource group size may in‐
          crease performance on very large file systems.  If not specified, mkfs.gfs2 will choose the resource group size based on the size and alignment characteristics  of  the  target
          device.

   -t clustername:lockspace
          The "lock table" pair used to uniquely identify this filesystem in a cluster.  The cluster name segment (maximum 32 characters) must match the name given to your cluster in its
          configuration;  only  members of this cluster are permitted to use this file system.  The lockspace segment (maximum 30 characters) is a unique file system name used to distin‐
          guish this gfs2 file system.  Valid clusternames and lockspaces may only contain alphanumeric characters, hyphens (-) and underscores (_).

   -U UUID
          Specify the filesystem UUID. The argument must be string of hexadecimal digits separated by hyphens, of the form "1b4e28ba-2fa1-11d2-883f-b9a761bde3fb". If this option is omit‐
          ted, the filesystem's UUID is randomly generated. Note that no attempt is made to prevent UUID clashes between filesystems.

   -V     Print program version information, then exit.

   block-count
          Use block-count as the size of the filesystem instead of using the whole device. block-count is specified as a number of filesystem blocks.

EXAMPLE

          # mkfs.gfs2 -t mycluster:mygfs2 -p lock_dlm -j 2 /dev/vg0/lv_gfs2

          This will create a gfs2 filesystem on the block device /dev/vg0/lv_gfs2.  It
          will belong to a cluster named "mycluster" and use the "mygfs2" lock space.  It
          will use DLM for locking and create journals for a two-node cluster.

          # mkfs.gfs2 -t mycluster:mygfs2 -p lock_nolock -j 3 /dev/vg0/lv_gfs2

          This will create a filesystem on the block device /dev/vg0/lv_gfs2.  It
          will belong to a cluster named "mycluster" and use the "mygfs2" lockspace, but
          it will have no cluster locking by default as lock_nolock is used.  It will
          have journals for a three-node cluster.