.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)