mount.gfs2

mount.gfs2(8)               System Manager's Manual              mount.gfs2(8)



NAME
       mount.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)
       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).




                                                                 mount.gfs2(8)