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

NAME

       mount.gfs - GFS mount options

SYNOPSIS

       mount [StandardMountOptions] -t gfs DEVICE MOUNTPOINT -o [GFSOption1,GFSOption2,GFSOptionX...]

DESCRIPTION

       GFS may be used as a local (single computer) filesystem, but its real purpose is in clusters, where multiple computers (nodes) share a com-
       mon storage device.

       Above is the format typically used to mount a GFS filesystem, using the mount(8) command.  The device may be any block device on which  you
       have  created  a  GFS  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 GFS  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 GFS-specific options that can be passed to the GFS 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 GFS, and are not
       interpreted  by the mount command nor by the kernel's Virtual File System.  GFS and non-GFS options may be intermingled after the -o, sepa-
       rated by commas (but no spaces).

       As an alternative to mount command line options, you may send mount options to gfs using "gfs_tool margs" (after  loading  the  gfs  kernel
       module,	but  before  mounting GFS).  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:

       # gfs_tool margs "lockproto=lock_nolock,ignore_local_fs"

       Options	loaded	via  "gfs_tool	margs"	have  a lifetime of only one GFS mount.  If you wish to mount another GFS filesystem, you must set
       another group of options with "gfs_tool margs".

       If you have trouble mounting GFS, 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 GFS 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 mkfs.gfs(8), -p  option.   It  can	be
	      changed on-disk by using the gfs_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 GFS 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.gfs(8), -t option.  It can
	      be changed on-disk by using the gfs_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  GFS  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 GFS 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 GFS.
	      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.

       oopses_ok
	      Normally, GFS automatically turns on the "kernel.panic_on_oops" sysctl to cause the machine to panic if an oops (an  in-kernel  seg-
	      fault  or  GFS  assertion failure) happens.  An oops on one machine of a cluster filesystem can cause the filesystem to stall on all
	      machines in the cluster.	(Panics don't have this "feature".)  By turning on "panic_on_oops", GFS tries to  make	sure  the  cluster
	      remains in operation even if one machine has a problem.  There are cases, however, where this behavior is not desirable -- debugging
	      being the main one.  The oopses_ok option causes GFS to leave the "panic_on_oops" variable alone so oopses  can  happen.	 Use  this
	      option with care.

	      This is turned on automatically by the lock_nolock module, but can be overridden by using the ignore_local_fs option.

       ignore_local_fs
	      By  default,  using  the	nolock lock module automatically turns on the localcaching and localflocks optimizations.  ignore_local_fs
	      forces GFS to treat the filesystem as if it were a multihost (clustered) filesystem, with localcaching and localflocks optimizations
	      turned off.

       upgrade
	      This  flag tells GFS to upgrade the filesystem's on-disk format to the version supported by the current GFS software installation on
	      this computer.  If you try to mount an old-version disk image, GFS 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 GFS filesystem.

       num_glockd
	      Tunes  GFS  to  alleviate memory pressure when rapidly acquiring many locks (e.g.  several processes scanning through huge directory
	      trees).  GFS' 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 32.	Since this option was introduced, other methods of
	      rapid cleanup have been developed within GFS, so this option may go away in the future.

       acl    Enables POSIX Access Control List acl(5) support within GFS.

       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.

LINKS

       http://sources.redhat.com/cluster
				     -- home site of GFS

       http://www.suse.de/~agruen/acl/linux-acls/
				     -- good writeup on ACL support in Linux

SEE ALSO

       gfs(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.gfs(8)