4.2. Mounting a File System

Before you can mount a GFS file system, the file system must exist (refer to Section 4.1, “Creating 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 Chapter 3, Getting Started and Configuring and Managing a Red Hat Cluster. After those requirements have been met, you can mount the GFS 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).

Usage

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

Example

In this example, the GFS file system on /dev/vg01/lvol0 is mounted on the /mydata1 directory.
mount /dev/vg01/lvol0 /mydata1

Complete Usage

mount BlockDevice MountPoint -o option
The -o option argument consists of GFS-specific options (refer to Table 4.2, “GFS-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.

Note

The mount command is a Linux system command. In addition to using GFS-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, “GFS-Specific Mount Options” describes the available GFS-specific -o option values that can be passed to GFS at mount time.

Note

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 GFS as a single-node file system. Red Hat will continue to support single-node GFS file systems for existing customers.

Table 4.2. GFS-Specific Mount Options

OptionDescription
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).
ignore_local_fs
Caution: This option should not be used when GFS file systems are shared.
Forces GFS to treat the file system as a multihost file system. By default, using lock_nolock automatically turns on the localcaching and localflocks flags.
localcaching
Caution: This option should not be used when GFS file systems are shared.
Tells GFS that it is running as a local file system. GFS can then turn on selected optimization capabilities that are not available when running in cluster mode. The localcaching flag is automatically turned on by lock_nolock.
localflocks
Caution: This option should not be used when GFS file systems are shared.
Tells GFS 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 GFS'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 GFS 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 For a clustered file system, allows the user to specify which locking table to use with the file system.
oopses_ok
This option allows a GFS node to not panic when an oops occurs. (By default, a GFS node panics when an oops occurs, causing the file system used by that node to stall for other GFS nodes.) A GFS node not panicking when an oops occurs minimizes the failure on other GFS nodes using the file system that the failed node is using. There may be circumstances where you do not want to use this option — for example, when you need more detailed troubleshooting information. Use this option with care.
Note: This option is turned on automatically if lock_nolock locking is specified; however, you can override it by using the ignore_local_fs option.
upgrade Upgrade the on-disk format of the file system so that it can be used by newer versions of GFS.
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 GFS withdraw function, see Section 4.16, “The GFS Withdraw Function”.