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4.2. Mounting a File System

Before you can mount a GFS2 file system, the file system must exist (refer to Section 4.1, “Making a File System”), the volume where the file system exists must be activated, and the supporting clustering and locking systems must be started (refer to Configuring and Managing a Red Hat Cluster). After those requirements have been met, you can mount the GFS2 file system as you would any Linux file system.
To manipulate file ACLs, you must mount the file system with the -o acl mount option. If a file system is mounted without the -o acl mount option, users are allowed to view ACLs (with getfacl), but are not allowed to set them (with setfacl).


Mounting Without ACL Manipulation
mount BlockDevice MountPoint
Mounting With ACL Manipulation
mount -o acl BlockDevice MountPoint
-o acl
GFS2-specific option to allow manipulating file ACLs.
Specifies the block device where the GFS2 file system resides.
Specifies the directory where the GFS2 file system should be mounted.


In this example, the GFS2 file system on /dev/vg01/lvol0 is mounted on the /mygfs2 directory.
mount /dev/vg01/lvol0 /mygfs2

Complete Usage

mount BlockDevice MountPoint -o option
The -o option argument consists of GFS2-specific options (refer to Table 4.2, “GFS2-Specific Mount Options”) or acceptable standard Linux mount -o options, or a combination of both. Multiple option parameters are separated by a comma and no spaces.


The mount command is a Linux system command. In addition to using GFS2-specific options described in this section, you can use other, standard, mount command options (for example, -r). For information about other Linux mount command options, see the Linux mount man page.
Table 4.2, “GFS2-Specific Mount Options” describes the available GFS2-specific -o option values that can be passed to GFS2 at mount time.


This table includes descriptions of options that are used with local file systems only For the Red Hat Enterprise Linux 5.5 release and later Red Hat does not support the use of GFS2 as a single-node file system. Red Hat will continue to support single-node GFS2 file systems for existing customers.

Table 4.2. GFS2-Specific Mount Options

acl Allows manipulating file ACLs. If a file system is mounted without the acl mount option, users are allowed to view ACLs (with getfacl), but are not allowed to set them (with setfacl).
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. When data=writeback mode is set, the user data is written to the disk at any time after it is dirtied; this does not provide the same consistency guarantee as ordered mode, but it should be slightly faster for some workloads. The default value is ordered mode.
Caution: This option should not be used when GFS2 file systems are shared.
Forces GFS2 to treat the file system as a multihost file system. By default, using lock_nolock automatically turns on the localflocks flags.
Caution: This option should not be used when GFS2 file systems are shared.
Tells GFS2 to let the VFS (virtual file system) layer do all flock and fcntl. The localflocks flag is automatically turned on by lock_nolock.
Note that the localflocks mount option affects only advisory fcntl()/POSIX locks and flock locks that are issued by applications. The internal locking that ensures coherency of data across the cluster by means of GFS2's glock abstraction is separate from and not affected by the localflocks setting.
If you are unsure whether an application uses fcntl()/POSIX locks and thus requires that you mount your file system with the localflocks, you can use the strace utility to print out the system calls that are made during a test run of the application. Look for fcntl calls that have F_GETLK, F_SETLK, or F_SETLKW as the cmd argument.
Note that GFS2 does not currently support either leases or mandatory locking.
lockproto=LockModuleName Allows the user to specify which locking protocol to use with the file system. If LockModuleName is not specified, the locking protocol name is read from the file system superblock.
locktable=LockTableName Allows the user to specify which locking table to use with the file system.
quota=[off/account/on] Turns quotas on or off for a file system. Setting the quotas to be in the account state causes the per UID/GID usage statistics to be correctly maintained by the file system; limit and warn values are ignored. The default value is off.
errors=panic|withdraw When errors=panic is specified, file system errors will cause a kernel panic. The default behavior, which is the same as specifying errors=withdraw, is for the system to withdraw from the file system and make it inaccessible until the next reboot; in some cases the system may remain running. For information on the GFS2 withdraw function, see Section 4.14, “The GFS2 Withdraw Function”.