.TH mkfs.gfs2 8

.SH NAME
mkfs.gfs2 - create a gfs2 filesystem

.SH SYNOPSIS
.B mkfs.gfs2
[\fIoptions\fR] \fIdevice\fR \fI[block-count]\fR

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

.SH 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 (\fB-j\fP) and the lock table
(\fB-t\fP), as these options will be specific to your cluster.
.TP
\fB-b\fP \fIbytes\fR
Set the filesystem block size to \fIbytes\fR 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.
.TP
\fB-c\fP \fImegabytes\fR
Initial size of each journal's quota change file. The default is 1MB.
.TP
\fB-D\fP
Enable debugging output.
.TP
\fB-h\fP
Print out a help message describing the available options, then exit.
.TP
\fB-J\fP \fImegabytes\fR
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.
.TP
\fB-j\fP \fIjournals\fR
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.
.TP
\fB-K\fP
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.
.TP
\fB-O\fP
Override. This option prevents mkfs.gfs2 from asking for confirmation before
writing the filesystem.
.TP
\fB-o\fP
Specify extended options. Multiple options can be separated by commas. Valid
extended options are:
.RS 1.0i
.TP
.BI help
Display an extended options help summary, then exit.
.TP
.BI 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
.I swidth
option.
.TP
.BI 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
.I sunit
option and must also be specified with it.
.TP
.BI 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
.I swidth
and
.I sunit
extended options.
.RE
.TP
\fB-p\fP \fIprotocol\fR
Specify the locking protocol to use when no locking protocol is specified at
mount time. Valid locking protocols are:
.RS 1.0i
.TP
.BI lock_dlm
This is the default. It enables DLM-based locking for use in shared storage
configurations.
.TP
.BI lock_nolock
This enables single-node locking
.RE
.TP
\fB-q\fP
Quiet mode. Do not print anything.
.TP
\fB-r\fP \fImegabytes\fR
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.
.TP
\fB-t\fP \fIclustername:lockspace\fR
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
\fIclustername\fRs and \fIlockspace\fRs may only contain alphanumeric
characters, hyphens (-) and underscores (_).
.TP
\fB-V\fP
Print program version information, then exit.
.TP
\fIblock-count\fR
Use \fIblock-count\fR as the size of the filesystem instead of using the whole
device. \fIblock-count\fR is specified as a number of filesystem blocks.
.SH EXAMPLE
.nf
.RS
# mkfs.gfs2 -t mycluster:mygfs2 -p lock_dlm -j 2 /dev/vg0/lv_gfs2
.PP
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.
.PP
# mkfs.gfs2 -t mycluster:mygfs2 -p lock_nolock -j 3 /dev/vg0/lv_gfs2
.PP
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.
.RE
.fi
.SH SEE ALSO
.BR gfs2 (5),
.BR gfs2_jadd (8),
.BR gfs2_grow (8)