mkfs.gfs2 - create a gfs2 filesystem
mkfs.gfs2 [
options]
device [block-count]
mkfs.gfs2 is used to create a gfs2 file system.
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.
# 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.
gfs2(5),
gfs2_jadd(8),
gfs2_grow(8)