gfs2_mount

gfs2_mount(8)               System Manager's Manual              gfs2_mount(8)



NAME
       gfs2_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
       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).

       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/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 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
              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 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
              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.

       num_glockd=Number
              Tunes GFS2 to alleviate memory pressure when rapidly aquiring
              many locks (e.g.  several processes scanning through huge
              directory 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 daemon, 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
              statistics 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
              transaction 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 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).




                                                                 gfs2_mount(8)