gfs2_mount(8)gfs2_mount(8)NAMEgfs2_mount - 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 parti‐
tion (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 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.
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). 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).
As an alternative to mount command line options, you may send mount
options to gfs2 using "gfs2_tool margs" (after loading the gfs2 kernel
module, but before mounting GFS2). For example, you may need to do
this when working from an initial ramdisk initrd(4). The options are
restricted to the ones described on this man page (no general mount(8)
options will be recognized), must not be preceded by -o, and must be
separated by commas (no spaces). Example:
# gfs2_tool margs "lockproto=lock_nolock,ignore_local_fs"
Options loaded via "gfs2_tool margs" have a lifetime of only one GFS2
mount. If you wish to mount another GFS2 filesystem, you must set
another group of options with "gfs2_tool margs".
The options debug, acl, quota, suiddir, and data can be changed after
mount using the "mount -o remount,option /mountpoint" command. The
options debug, 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=LockModuleName
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 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 gfs2_mkfs(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 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 gfs2_mkfs(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.
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 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.
num_glockd=Number
Tunes GFS2 to alleviate memory pressure when rapidly aquiring
many locks (e.g. several processes scanning through huge direc‐
tory trees). GFS2' glockd kernel daemon cleans up memory for
no-longer-needed glocks. Multiple instances of the daemon clean
up faster than a single instance. The default value is one dae‐
mon, with a maximum of 16. Since this option was introduced,
other methods of rapid cleanup have been developed within GFS2,
so this option may go away in the future.
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 statis‐
tics to be correctly maintained by the filesystem, limit and
warn values are ignored. The default value is "off".
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 commited
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 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).
gfs2_mount(8)
