Provided by: gfs2-utils_3.6.1-1_amd64 
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 number 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 specified, 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 overrides 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 increase 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 distinguish 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 omitted, 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.
SEE ALSO
gfs2(5), gfs2_jadd(8), gfs2_grow(8)
mkfs.gfs2(8)