IBM General Parallel File System for AIX: Administration and Programming Reference

mmdelnode Command

Name

mmdelnode - Removes one or more nodes from a GPFS nodeset.

Synopsis

mmdelnode [-c] [-C NodesetId ] [-P] {-a | NodeName[,NodeName...] }

Or,

mmdelnode -c [-C NodesetId ]

Description

Use the mmdelnode command to delete one or more nodes from the same GPFS nodeset. You may issue the mmdelnode command on any GPFS node.

You must follow these rules when deleting nodes:

1. Before you can delete a node, you must unmount all of the GPFS file systems and stop GPFS on the node to be deleted.
2. Exercise caution when deleting nodes from the GPFS nodeset. In a multi-node quorum environment, if the number of remaining nodes falls below the requirement for a quorum, you will be unable to perform file system operations (see the IBM General Parallel File System for AIX: Concepts, Planning, and Installation Guide and search for quorum).
3. If the number of nodes remaining in the nodeset falls below 3, you must run the mmchconfig command if you want to change the quorum algorithm to single-node quorum.
4. When a node is deleted from a GPFS nodeset, its entry is not automatically deleted from the nodeset configuration. Instead, the node is only marked as deleted. This allows nodes to be deleted without having to stop GPFS on all nodes. Such deleted nodes are not a factor when calculating quorum. They are also available to the mmaddnode and mmconfig commands for inclusion into another GPFS nodeset. If you want to remove any deleted node entries from the nodeset configuration, you must use the -c option on the mmdelnode command. This can be done when the node is deleted, or anytime later.

Results

Upon successful execution of the mmdelnode command, these tasks are completed:

• Mount point directories and character mode devices are removed from the deleted nodes.
• The quorum requirement is updated.
• The nodeset configuration information on each node in the nodeset is updated.

If the mmdelnode command is unsuccessful because one or more nodes are down, execution completes as the nodes come up.

Parameters

-C NodesetId

The identifier of the GPFS nodeset you want to delete nodes from. If -C is not specified, the nodeset identifier is determined from the nodes specified on the command line. If a period (.) is used for the NodesetId, the nodeset is assumed to be that of the node you are running on. To determine the nodeset of the node you are running on, issue the mmlsnode -C . command.

In an SP environment, if you specify -a and the command is issued from the CWS, you must also specify -C.

NodeName[,NodeName...]

A comma-separated list of nodes to be deleted. The nodes must all be members of the same GPFS nodeset.

The hostname or IP address used for a node must refer to the adapter port over which the GPFS daemons communicate. Alias interfaces are not allowed. Use the original address or a name that is resolved by the host command to that original address. You may specify a node using any of these forms:

Format	Example
Short hostname	k145n01
Long hostname	k145n01.kgn.ibm.com
IP address	9.119.19.102

Options

-a

Delete all nodes in the current or specified nodeset.

-c

Remove all entries for the deleted nodes from the nodeset configuration information. This includes entries for all nodes specified, as well as any entries for previously deleted nodes.

The GPFS daemon must be stopped on all nodes in the nodeset not just the nodes specified for deletion.

Prior to deleting nodes from a GPFS cluster, you must specify the mmdelnode -c command to delete the nodes from the nodeset and adjust the list of nodes in the GPFS cluster data.

-P

Preserve the configuration information after the last node is deleted.

Exit status

0

Successful completion.

1

A failure has occurred.

Security

You must have root authority to run the mmdelnode command.

In an SP environment:

• Verify the authentication method set for SP security services:
  1. If your authentication method is set to compatibility, Kerberos authentication is required. Issue the k4init command.
  2. If your authentication method is set to DCE, dce_login authentication is required.
  3. If your authentication method is set to NONE/std, there must be an entry in the /etc/sysctl.mmcmd.acl file on every node in the nodeset for the root user at every other node in the nodeset.

  For further information, see the latest IBM Parallel System Support Programs for AIX: Administration Guide, IBM Parallel System Support Programs for AIX: Command and Technical Reference, and RS/6000: Planning Volume 2, Control Workstation and Software Environment manuals at www.rs6000.ibm.com/resource/aix_resource/sp_books/pssp. Search for information on sysctl.

• You may issue the mmdelnode command from any node running GPFS or the CWS when using the -C option.
• If you are executing the mmdelnode command from the CWS on a multi-partitioned system, the SP_NAME environment variable must be properly set. It is suggested that you use a separate window for each partition and set the environment variable accordingly. For further information, see the IBM Parallel System Support Programs for AIX: Administration Guide and search for understanding system partitioning.

In an HACMP environment:

1. When using rcp and rsh for remote communication, a properly configured /.rhosts file must exist in the root user's home directory on each node in the GPFS cluster. If you have designated the use of a different remote communication program on either the mmcrcluster or the mmchcluster command, you must insure:
   1. Proper authorization is granted to all nodes in the GPFS cluster.
   2. The nodes in the GPFS cluster can communicate without the use of a password.
2. You may issue the mmdelnode command from any node in the GPFS cluster.

Examples

1. To delete all of the nodes in the nodeset from which the command is being issued, enter:

   mmdelnode -a
   

   The system displays information similar to:

   Verifying GPFS is stopped on all nodes ...
   mmdelnode: 6027-1370 Removing old nodeset information from the deleted nodes.
   This is an asynchronous process.
    
   

2. To delete nodes k145n12, k145n13, and k145n14, enter:

   mmdelnode k145n12,k145n13,k145n14
   

   The system displays information similar to:

   Verifying GPFS is stopped on all nodes ...
   mmdelnode: 6027-1370 Removing old nodeset information from the deleted nodes.
   This is an asynchronous process.
   mmdelnode: 6027-1371 Propagating the changes to all affected nodes.
   This is an asynchronous process.
    
   

3. To remove the nodeset configuration information for any nodes that are being or have been deleted, enter:

   mmdelnode -c
   

   The system displays information similar to:

   Verifying GPFS is stopped on all nodes ...
   mmdelnode: 6027-1371 Propagating the changes to all affected nodes.
   This is an asynchronous process.
   

See also

mmaddnode Command

mmconfig Command

mmchconfig Command

mmlsfs Command

mmlsnode Command

Location

/usr/lpp/mmfs/bin