mmumount command

Availability

Available on all IBM Spectrum Scale™ editions.

Description

Another name for the mmumount command is the mmunmount command. Either name can be used.

The mmumount command unmounts a previously mounted GPFS file system on one or more nodes in the cluster. If no nodes are specified, the file systems are unmounted only on the node from which the command was issued. The file system can be specified using its device name or the mount point where it is currently mounted.

Use the first form of the command to unmount file systems on nodes that belong to the local cluster.

Use the second form of the command with the -C option when it is necessary to force an unmount of file systems that are owned by the local cluster, but are mounted on nodes that belong to another cluster.

When a file system is unmounted by force with the second form of the mmumount command, the affected nodes may still show the file system as mounted, but the data will not be accessible. It is the responsibility of the system administrator to clear the mount state by issuing the umount command.

When multiple nodes are affected and the unmount target is identified via a mount point or a Windows drive letter, the mount point is resolved on each of the target nodes. Depending on how the file systems were mounted, this may result in different file systems being unmounted on different nodes. When in doubt, always identify the target file system with its device name.

Parameters

Device | MountPoint | DriveLetter | all | all_local | all_remote | {-F DeviceFileName}

Indicates the file system or file systems to be unmounted.

Device

Is the device name of the file system to be unmounted. File system names do not need to be fully qualified. fs0 is as acceptable as /dev/fs0.

MountPoint

Is the location where the GPFS file system to be unmounted is currently mounted.

DriveLetter

Identifies a file system by its Windows drive letter.

all

Indicates all file systems that are known to this cluster.

all_local

Indicates all file systems that are owned by this cluster.

all_remote

Indicates all files systems that are owned by another cluster to which this cluster has access.

-F DeviceFileName

Specifies a file containing the device names, one per line, of the file systems to be unmounted.

This must be the first parameter.

Options

-a

Unmounts the file system on all nodes in the GPFS cluster.

-f

Forces the unmount to take place even though the file system may be still in use.

Use this flag with extreme caution. Using this flag may cause outstanding write operations to be lost. Because of this, forcing an unmount can cause data integrity failures and should be used with caution.

The mmumount command relies on the native umount command to carry out the unmount operation. The semantics of forced unmount are platform-specific. On some platforms (such as Linux), even when forced unmount is requested, a file system cannot be unmounted if it is still referenced by the system kernel. Examples of such cases are:

• Open files are present in the file system
• A process uses a subdirectory in the file system as the current working directory
• The file system is NFS-exported

To unmount a file system successfully in such a case, it may be necessary to identify and stop the processes that are referencing the file system. System utilities like lsof and fuser could be used for this purpose.

-C {all_remote | ClusterName}

Specifies the cluster on which the file system is to be unmounted by force. all_remote denotes all clusters other than the one from which the command was issued.

-N {Node[,Node...] | NodeFile | NodeClass}

Specifies the nodes on which the file system is to be unmounted.

For general information on how to specify node names, see Specifying nodes as input to GPFS commands.

This command does not support a NodeClass of mount.

When the -N option is specified in conjunction with -C ClusterName, the specified node names are assumed to refer to nodes that belong to the specified remote cluster (as identified by the mmlsmount command). The mmumount command cannot verify the accuracy of this information. NodeClass and NodeFile are not supported in conjunction with the -C option.

Exit status

0

Successful completion.

nonzero

A failure has occurred.

Security

You must have root authority to run the mmumount command.

The node on which the command is issued must be able to execute remote shell commands on any other node in the cluster without the use of a password and without producing any extraneous messages. For more information, see Requirements for administering a GPFS file system.

See also

Location