mount -a [-fnrsvw] -t gfs2 [-O options] mount [-fnrsvw] -t gfs2 [-o options ] device dir
DESCRIPTION
For details on the common mount options, please see the
mount(8) command man page.
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
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.
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 commit, discard, errors, quota_quantum, statfs_quantum, statfs_percent, barrier, acl, quota, suiddir, and data can be
changed after mount using the "mount -o remount,option /mountpoint" command.
The options quota, discard, barrier, 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=LockProtoName
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 LockProtoName must be one of the supported locking protocols,
currently these are lock_nolock and lock_dlm.
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. Using the incorrect lock protocol
on a cluster filesystem mounted from more than one node will almost
certainly result in filesystem corruption.
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.
errors=[panic|withdraw]
Setting errors=panic causes GFS2 to oops when encountering an error that
would otherwise cause the
mount to withdraw or print an assertion warning. The default setting
is errors=withdraw. This option should not be used in a production system.
It replaces the earlier debug option on kernel versions 2.6.31 and
above.
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. The node is unable to
recover journals for other nodes.
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.
barrier
This option, which defaults to on, causes GFS2 to send I/O barriers
when flushing the journal. The option is automatically turned off
if the underlying device does not support I/O barriers. We highly
recommend the use of I/O barriers with GFS2 at all times unless
the block device is designed so that it cannot lose its write cache
content (e.g. its on a UPS, or it doesn't have a write cache)
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.
meta
This option results in selecting the meta filesystem root rather than
the normal filesystem root. This option is normally only used by
the GFS2 utility functions. Altering any file on the GFS2 meta filesystem
may render the filesystem unusable, so only experts in the GFS2
on-disk layout should use this option.
quota_quantum=secs
This sets the number of seconds for which a change in the quota
information may sit on one node before being written to the quota
file. This is the preferred way to set this parameter. The value
is an integer number of seconds greater than zero. The default is
60 seconds. Shorter settings result in faster updates of the lazy
quota information and less likelihood of someone exceeding their
quota. Longer settings make filesystem operations involving quotas
faster and more efficient.
statfs_quantum=secs
Setting statfs_quantum to 0 is the preferred way to set the slow version
of statfs. The default value is 30 secs which sets the maximum time
period before statfs changes will be syned to the master statfs file.
This can be adjusted to allow for faster, less accurate statfs values
or slower more accurate values. When set to 0, statfs will always
report the true values.
statfs_percent=value
This setting provides a bound on the maximum percentage change in
the statfs information on a local basis before it is synced back
to the master statfs file, even if the time period has not
expired. If the setting of statfs_quantum is 0, then this setting
is ignored.
BUGS
GFS2 doesn't support errors=remount-ro or data=journal.
It is not possible to switch support for user and group quotas on and
off independently of each other. Some of the error messages are rather
cryptic, if you encounter one of these messages check firstly that gfs_controld
is running and secondly that you have enough journals on the filesystem
for the number of nodes in use.
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).