NAME
mount.gfs2 - GFS2 mount options
SYNOPSIS
mount [StandardMountOptions] -t gfs2 DEVICE MOUNTPOINT -o
[GFS2Option1,GFS2Option2,GFS2OptionX...]
DESCRIPTION
GFS2 may be used as a local (single computer) filesystem, but its real
purpose is in clusters, where multiple computers (nodes) share a common
storage device.
Above is the format typically used to mount a GFS2 filesystem, using
the mount(8) command. The device may be any block device on which you
have created a GFS2 filesystem. Examples include a single disk
partition (e.g. /dev/sdb3), a loopback device, a device exported from
another node (e.g. an iSCSI device or a gnbd(8) device), or a logical
volume (typically comprised of a number of individual disks).
device does not necessarily need to match the device name as seen on
another node in the cluster, nor does it need to be a logical volume.
However, the use of a cluster-aware volume manager such as CLVM2 (see
lvm(8)) will guarantee that the managed devices are named identically
on each node in a cluster (for much easier management), and will allow
you to configure a very large volume from multiple storage units (e.g.
disk drives).
device must make the entire filesystem storage area visible to the
computer. That is, you cannot mount different parts of a single
filesystem on different computers. Each computer must see an entire
filesystem. You may, however, mount several GFS2 filesystems if you
want to distribute your data storage in a controllable way.
mountpoint is the same as dir in the mount(8) man page.
This man page describes GFS2-specific options that can be passed to the
GFS2 file system at mount time, using the -o flag. There are many
other -o options handled by the generic mount command mount(8).
However, the options described below are specifically for GFS2, and are
not interpreted by the mount command nor by the kernel’s Virtual File
System. GFS2 and non-GFS2 options may be intermingled after the -o,
separated by commas (but no spaces).
The options debug, commit, discard, acl, quota, suiddir, and data can
be changed after mount using the "mount -o remount,option /mountpoint"
command. The options debug, quota, discard, acl, and suiddir support
the "no" prefix. For example, "noacl" turns off what "acl" turns on.
If you have trouble mounting GFS2, check the syslog (e.g.
/var/log/messages) for specific error messages.
OPTIONS
lockproto=LockModuleName
This specifies which inter-node lock protocol is used by the
GFS2 filesystem for this mount, overriding the default lock
protocol name stored in the filesystem’s on-disk superblock.
The LockModuleName must be an exact match of the protocol name
presented by the lock module when it registers with the lock
harness. Traditionally, this matches the .o filename of the
lock module, e.g. lock_dlm, or lock_nolock.
The default lock protocol name is written to disk initially when
creating the filesystem with mkfs.gfs2(8), -p option. It can be
changed on-disk by using the gfs2_tool(8) utility’s sb proto
command.
The lockproto mount option should be used only under special
circumstances in which you want to temporarily use a different
lock protocol without changing the on-disk default.
locktable=LockTableName
This specifies the identity of the cluster and of the filesystem
for this mount, overriding the default cluster/filesystem
identify stored in the filesystem’s on-disk superblock. The
cluster/filesystem name is recognized globally throughout the
cluster, and establishes a unique namespace for the inter-node
locking system, enabling the mounting of multiple GFS2
filesystems.
The format of LockTableName is lock-module-specific. For
lock_dlm, the format is clustername:fsname. For lock_nolock,
the field is ignored.
The default cluster/filesystem name is written to disk initially
when creating the filesystem with mkfs.gfs2(8), -t option. It
can be changed on-disk by using the gfs2_tool(8) utility’s sb
table command.
The locktable mount option should be used only under special
circumstances in which you want to mount the filesystem in a
different cluster, or mount it as a different filesystem name,
without changing the on-disk default.
localcaching
This flag tells GFS2 that it is running as a local (not
clustered) filesystem, so it can turn on some block caching
optimizations that can’t be used when running in cluster mode.
This is turned on automatically by the lock_nolock module, but
can be overridden by using the ignore_local_fs option.
localflocks
This flag tells GFS2 that it is running as a local (not
clustered) filesystem, so it can allow the kernel VFS layer to
do all flock and fcntl file locking. When running in cluster
mode, these file locks require inter-node locks, and require the
support of GFS2. When running locally, better performance is
achieved by letting VFS handle the whole job.
This is turned on automatically by the lock_nolock module, but
can be overridden by using the ignore_local_fs option.
debug Causes GFS2 to oops when encountering an error that would cause
the mount to withdraw or print an assertion warning. This
option should probably not be used in a production system.
ignore_local_fs
By default, using the nolock lock module automatically turns on
the localcaching and localflocks optimizations. ignore_local_fs
forces GFS2 to treat the filesystem as if it were a multihost
(clustered) filesystem, with localcaching and localflocks
optimizations turned off.
upgrade
This flag tells GFS2 to upgrade the filesystem’s on-disk format
to the version supported by the current GFS2 software
installation on this computer. If you try to mount an old-
version disk image, GFS2 will notify you via a syslog message
that you need to upgrade. Try mounting again, using the -o
upgrade option. When upgrading, only one node may mount the
GFS2 filesystem.
acl Enables POSIX Access Control List acl(5) support within GFS2.
spectator
Mount this filesystem using a special form of read-only mount.
The mount does not use one of the filesystem’s journals.
suiddir
Sets owner of any newly created file or directory to be that of
parent directory, if parent directory has S_ISUID permission
attribute bit set. Sets S_ISUID in any new directory, if its
parent directory’s S_ISUID is set. Strips all execution bits on
a new file, if parent directory owner is different from owner of
process creating the file. Set this option only if you know why
you are setting it.
quota=[off/account/on]
Turns quotas on or off for a filesystem. Setting the quotas to
be in the "account" state causes the per UID/GID usage
statistics to be correctly maintained by the filesystem, limit
and warn values are ignored. The default value is "off".
discard
Causes GFS2 to generate "discard" I/O requests for blocks which
have been freed. These can be used by suitable hardware to
implement thin-provisioning and similar schemes. This feature is
supported in kernel version 2.6.30 and above.
commit=secs
This is similar to the ext3 commit= option in that it sets the
maximum number of seconds between journal commits if there is
dirty data in the journal. The default is 60 seconds. This
option is only provided in kernel versions 2.6.31 and above.
data=[ordered/writeback]
When data=ordered is set, the user data modified by a
transaction is flushed to the disk before the transaction is
committed to disk. This should prevent the user from seeing
uninitialized blocks in a file after a crash. Data=writeback
mode writes the user data to the disk at any time after it’s
dirtied. This doesn’t provide the same consistency guarantee as
ordered mode, but it should be slightly faster for some
workloads. The default is ordered mode.
LINKS
http://sources.redhat.com/cluster
-- home site of GFS2
http://www.suse.de/~agruen/acl/linux-acls/
-- good writeup on ACL support in Linux
SEE ALSO
gfs2(8), mount(8) for general mount options, chmod(1) and chmod(2) for
access permission flags, acl(5) for access control lists, lvm(8) for
volume management, ccs(7) for cluster management, umount(8), initrd(4).
mount.gfs2(8)