mmchcluster command

Availability

Available on all IBM Spectrum Scale™ editions.

Description

To display current system information for the cluster, issue the mmlscluster command.

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

When issuing the mmchcluster command with the -p or -s options, the specified nodes must be available in order for the command to succeed. If any of the nodes listed are not available when the command is issued, a message listing those nodes is displayed. You must correct the problem on each node and reissue the command.

Parameters

--ccr-enable

Enables the configuration server repository (CCR), which stores redundant copies of configuration data files on all quorum nodes. The advantage of CCR over the traditional primary or backup configuration server semantics is that when using CCR, all GPFS administration commands as well as file system mounts and daemon startups work normally as long as a majority of quorum nodes are accessible.

For more information, see Cluster configuration data files.

The CCR operation requires the use of the GSKit toolkit for authenticating network connections. As such, the gpfs.gskit package, which is available on all Editions, should be installed.

--ccr-disable [--force]

Reverts to the traditional primary or backup configuration server semantics and destroys the CCR environment. GPFS must be shut down on all the nodes before disabling CCR.

--force

Causes the command to disable CCR even if Cluster Export Services (CES) is enabled on some of the nodes in the cluster. By default, if you specify --ccr-disable and CES is enabled on some nodes, the command returns immediately and displays an error message. The reason is that CES requires CCR to be enabled. To disable CCR even if CES is enabled, do one of the following actions:

• Remove all CES nodes from the cluster and issue the command with the --ccr-disable parameter.
• Issue the command with --ccr-disable parameter followed by the --force option.
  CAUTION:
  This command deletes the current CES configuration information. If you have created CES configuration information, ensure that you have made a backup copy before you issue this command. For more information, see Backing up and restoring protocols and CES configuration information.

-p PrimaryServer

Change the primary server node for the GPFS cluster data. This may be specified as a short or long node name, an IP address, or a node number.

LATEST – Synchronize all of the nodes in the GPFS cluster ensuring they are using the most recently specified primary GPFS cluster configuration server. If an invocation of the mmchcluster command fails, you are prompted to reissue the command and specify LATEST on the -p option to synchronize all of the nodes in the GPFS cluster. Synchronization provides for all nodes in the GPFS cluster to use the most recently specified primary GPFS cluster configuration server.

This option only applies when the traditional server-based configuration (non-CCR) repository is used.

-s SecondaryServer

Change the secondary server node for the GPFS cluster data. To remove the secondary GPFS server and continue operating without it, specify a null string, "", as the parameter. This may be specified as a short or long node name, an IP address, or a node number.

This option only applies when the traditional server-based configuration (non-CCR) repository is used.

-r RemoteShellCommand

Specifies the fully-qualified path name for the remote shell program to be used by GPFS.

The remote shell command must adhere to the same syntax format as the ssh command, but may implement an alternate authentication mechanism.

-R RemoteFileCopy

Specifies the fully-qualified path name for the remote file copy program to be used by GPFS.

The remote copy command must adhere to the same syntax format as the scp command, but may implement an alternate authentication mechanism.

--nouse-sudo-wrapper

Specifies that the cluster reverts to using the default remote shell program and remote copy program. For more information, see Running IBM Spectrum Scale commands without remote root login.

--use-sudo-wrapper [sudo-user UserName]

Causes the nodes in the cluster to call the ssh and scp sudo wrapper scripts as the remote shell program and the remote copy program. For more information, see Running IBM Spectrum Scale commands without remote root login.

--sudo-user UserName

Specifies a non-root admin user ID to be used when sudo wrappers are enabled and a root-level background process calls an administration command directly instead of through sudo. The GPFS daemon that processes the administration command specifies this non-root user ID instead of the root ID when it needs to run internal commands on other nodes. For more information, see Root-level processes that call administration commands directly.

To disable this feature, specify the key word DELETE instead of a user name, as in the following example:

mmchcluster --sudo-user DELETE

-C ClusterName

Specifies a new name for the cluster. If the user-provided name contains dots, it is assumed to be a fully qualified domain name. Otherwise, to make the cluster name unique, the domain of the first quorum node or, if specified, the primary configuration server will be appended to the user-provided name.

Since each cluster is managed independently, there is no automatic coordination and propagation of changes between clusters like there is between the nodes within a cluster. This means that if you change the name of the cluster, you should notify the administrators of all other GPFS clusters that can mount your file systems so that they can update their own environments.

Before running this option, ensure that all GPFS daemons on all nodes have been stopped.

See the mmauth, mmremotecluster, and mmremotefs commands.

Exit status

0

Successful completion.

nonzero

A failure has occurred.

Security

You must have root authority to run the mmchcluster 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