--- name: "gfs_mount" section: "8" platform: "linux" package: "gfs-tools" version: "2.20081102-1+lenny1" release: "Debian 5.0 (Lenny)" platforms: ["linux"] url: "https://new.carta.tech/gfs_mount" --- # gfs\_mount(8) GFS mount options ## NAME gfs\_mount - 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 common storage device. Above is the format typically used to mount a GFS filesystem, using the [**mount**(8)](/mount/8.md) 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)](/gnbd/8.md) 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)](/lvm/8.md)) 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)](/mount/8.md) 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)](/mount/8.md). 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**, separated 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)](/initrd/4.md). The options are restricted to the ones described on this man page (no general [**mount**(8)](/mount/8.md) 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 [**gfs\_mkfs**(8)](/gfs_mkfs/8.md), -p option. It can be changed on-disk by using the [**gfs\_tool**(8)](/gfs_tool/8.md) 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 [**gfs\_mkfs**(8)](/gfs_mkfs/8.md), -t option. It can be changed on-disk by using the [**gfs\_tool**(8)](/gfs_tool/8.md) 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 segfault 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)](/acl/5.md) 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)](/gfs/8.md), [**mount**(8)](/mount/8.md) for general mount options, [**chmod**(1)](/chmod/1.md) and [**chmod**(2)](/chmod/2.md) for access permission flags, [**acl**(5)](/acl/5.md) for access control lists, [**lvm**(8)](/lvm/8.md) for volume management, [**ccs**(7)](/ccs/7.md) for cluster management, [**umount**(8)](/umount/8.md), [**initrd**(4)](/initrd/4.md).