.\"  Portions copyright (c) 2001-2003 The OpenGFS Project
.\"  Portions copyright (c) 2004 ben.m.cahill@intel.com
.\"
.\"  This copyrighted material is made available to anyone wishing to use,
.\"  modify, copy, or redistribute it subject to the terms and conditions
.\"  of the GNU General Public License v.2.
.\"
.tl 'gfs_mount(8)''gfs_mount(8)'

\fBNAME\fP
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gfs_mount - GFS mount options
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\fBSYNOPSIS\fP
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\fBmount\fP [StandardMountOptions] \fB-t\fP gfs \fIdevice\fR \fImountpoint\fR \fB-o\fP [GFSOption1,GFSOption2,GFSOptionX...]
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\fBDESCRIPTION\fP
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GFS 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 GFS filesystem, using the
\fBmount\fP(8) command.  The \fIdevice\fR 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 \fBgnbd\fP(8) device), or a
logical volume (typically comprised of a number of individual disks).

\fIdevice\fR 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 \fBlvm\fP(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).

\fIdevice\fR 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.

\fImountpoint\fR is the same as \fIdir\fR in the \fBmount\fP(8) man page.

This man page describes GFS-specific options that can be passed to the GFS 
file system at mount time, using the \fB-o\fP flag.  There are many other
\fB-o\fP options handled by the generic mount command \fBmount\fP(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 \fB-o\fP, separated by
commas (but no spaces).

As an alternative to mount command line options, you may send mount options
to /proc/fs/gfs (after loading the gfs kernel module, but before mounting GFS).
For example, you may need to do this when working from an initial ramdisk
\fBinitrd\fP(4).  The options are restricted to the ones described on this man
page (no general \fBmount\fP(8) options will be recognized), must not be
preceded by -o, and must be separated by commas (no spaces).  Example:

# echo "lockproto=lock_nolock,ignore_local_fs" > /proc/fs/gfs 

Options loaded via /proc/fs/gfs have a lifetime of only one GFS mount.  If you
wish to mount another GFS filesystem, you must send another set of options
to /proc/fs/gfs.

If you have trouble mounting GFS, check the syslog (e.g. /var/log/messages)
for specific error messages.
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\fBOPTIONS\fP
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\fBlockproto=\fP\fILockModuleName\fR
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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 \fILockModuleName\fR 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. \fIlock_dlm\fR,
\fIlock_gulm\fR, or \fIlock_nolock\fR.

The default lock protocol name is written to disk initially when creating the
filesystem with \fBgfs_mkfs\fP(8), -p option.  It can be changed on-disk by
using the \fBgfs_tool\fP(8) utility's \fBsb proto\fP command.

The \fBlockproto\fP 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.
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\fBlocktable=\fP\fILockTableName\fR
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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 \fILockTableName\fR is lock-module-specific.  For lock_gulm
and lock_dlm, the format is \fIclustername:fsname\fR.  For
lock_nolock, the field is ignored.

The default cluster/filesystem name is written to disk initially when creating
the filesystem with \fBgfs_mkfs\fP(8), -t option.  It can be changed on-disk
by using the \fBgfs_tool\fP(8) utility's \fBsb table\fP command.

The \fBlocktable\fP 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.
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\fBhostdata=\fP\fIHostIDInfo\fR
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This field sends host (the computer on which the filesystem is being mounted)
identity information to the lock module.

The format and behavior of \fIHostIDInfo\fR is lock-module-specific.
For lock_gulm, it overrides the \fBuname\fP(1) -n network node name
used as default by lock_gulm.

This field is ignored by \fIlock_dlm\fR and \fIlock_nolock\fR.
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\fBlocalcaching\fP
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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 \fBignore_local_fs\fP option.
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\fBlocalflocks\fP
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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 \fBignore_local_fs\fP option.
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\fBignore_local_fs\fP
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By default, using the nolock lock module automatically turns on the
\fBlocalcaching\fP and \fBlocalflocks\fP optimizations.  \fBignore_local_fs\fP
forces GFS to treat the filesystem as if it were a multihost (clustered)
filesystem, with \fBlocalcaching\fP and \fBlocalflocks\fP optimizations
turned off.
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\fBupgrade\fP
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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
\fB-o upgrade\fP option.  When upgrading, only one node may mount the GFS
filesystem.
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\fBnum_glockd\fP
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Tunes GFS to alleviate memory pressure when rapidly aquiring 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.
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\fBacl\fP
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Enables POSIX Access Control List \fBacl\fP(5) support within GFS.
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\fBsuiddir\fP
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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.
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\fBLINKS\fP
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http://sources.redhat.com/cluster
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-- home site of GFS
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http://www.suse.de/~agruen/acl/linux-acls/
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-- good writeup on ACL support in Linux
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\fBSEE ALSO\fP
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\fBgfs\fP(8), 
\fBmount\fP(8) for general mount options,
\fBchmod\fP(1) and \fBchmod\fP(2) for access permission flags,
\fBacl\fP(5) for access control lists,
\fBlvm\fP(8) for volume management,
\fBccs\fP(7) for cluster management,
\fBlock_gulmd\fP(8),
\fBumount\fP(8),
\fBinitrd\fP(4).
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