mount.gfs2(8)mount.gfs2(8)NAMEmount.gfs2 - GFS2 mount options
SYNOPSIS
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) com‐
mand 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 com‐
puter. That is, you cannot mount different parts of a single filesys‐
tem on different computers. Each computer must see an entire filesys‐
tem. 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). How‐
ever, 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/mes‐
sages) 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 pro‐
tocol name stored in the filesystem's on-disk superblock.
The LockProtoName must be one of the supported locking proto‐
cols, 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 iden‐
tify stored in the filesystem's on-disk superblock. The clus‐
ter/filesystem name is recognized globally throughout the clus‐
ter, and establishes a unique namespace for the inter-node lock‐
ing 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 clus‐
tered) filesystem, so it can turn on some block caching opti‐
mizations 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 clus‐
tered) 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 sup‐
port 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 opti‐
mizations turned off.
upgrade
This flag tells GFS2 to upgrade the filesystem's on-disk format
to the version supported by the current GFS2 software installa‐
tion 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 statis‐
tics 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 bar‐
riers when flushing the journal. The option is automatically
turned off if the underlying device does not support I/O barri‐
ers. 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 transac‐
tion 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 opera‐
tions 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 set‐
ting is ignored.
BUGS
GFS2 doesn't support errors=remount-ro or data=journal. It is not pos‐
sible to switch support for user and group quotas on and off indepen‐
dently 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 ALSOgfs2(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)
