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  optimiza-
	      tions 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 max-
	      imum 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 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 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)