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

mmchcluster Command

Name

mmchcluster - Changes GPFS cluster configuration data.

Synopsis

mmchcluster {[-p PrimaryServer ] [-s SecondaryServer]}

Or,

mmchcluster -p LATEST

Or,

mmchcluster [-r RemoteShellCommand] [-R RemoteFileCopyCommand]

Description

The mmchcluster command serves different purposes:

1. Change the primary or secondary GPFS cluster data server.
2. Synchronize the primary GPFS cluster data server.
3. Change the remote shell and remote file copy programs to be used by the nodes in the cluster.

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

Attention: The mmchcluster command is designed to operate in an environment where the current primary cluster data server is not available. As a result, the command can run without obtaining its regular serialization locks. To assure smooth transition to a new data server, no other GPFS commands ( mm commands) should be running when the command is issued nor should any other command be issued until the mmchcluster command has successfully completed.

Parameters

-p

PrimaryServer - Change the primary server node for the GPFS cluster data.

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

-s SecondaryServer

Change the secondary server node for the GPFS cluster data. To remove the secondary GPFS server and continue operating without a backup, specify a null string, """, as the parameter.

You must follow these rules when changing the GPFS cluster data server nodes:

• The node must be a member of the GPFS cluster.
• The node must be available for the command to be successful. 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.
• 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

-r RemoteShellCommand

Specifies the fully qualified pathname for the remote shell program to be used by GPFS.

The remote shell command must adhere to the same syntax form as rsh but may implement an alternate authentication mechanism.

-R RemoteFileCopy

Specifies the fully qualified pathname for the remote file copy program to be used by GPFS.

The remote copy command must adhere to the same syntax form as rcp but may implement an alternate authentication mechanism.

Exit status

0

Successful completion.

1

A failure has occurred.

Security

You must have root authority to run the mmchcluster command.

You may issue the mmchcluster command from any node in the GPFS cluster.

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.

Examples

To change the primary GPFS server for the cluster, enter:

mmchcluster -p k145n03

To confirm the change, enter:

mmlscluster

The system displays information similar to:

GPFS cluster information                           
========================                           
  Cluster id:  gpfs0103263/15/01M03                
  Remote shell command:      /usr/bin/rsh          
  Remote file copy command:  /usr/bin/rcp          
                                                   
GPFS cluster data repository servers:              
-------------------------------------              
  Primary server:    k145n03.kgn.ibm.com        
  Secondary server:  k145n44.kgn.ibm.com        
                                                   
Nodes in nodeset 1:                                
-------------------                                
  1  k145n03  9.114.133.03  k145n03.kgn.ibm.com  
  2  k145n30  9.114.133.30  k145n30.kgn.ibm.com  
  3  k145n31  9.114.133.31  k145n31.kgn.ibm.com  
  4  k145n32  9.114.133.32  k145n32.kgn.ibm.com  
                                                   
Nodes in nodeset 2:                              
---------------------                              
  5  k145n33  9.114.133.33  k145n33.kgn.ibm.com  
  6  k145n34  9.114.133.34  k145n34.kgn.ibm.com  
  7  k145n35  9.114.133.35  k145n35.kgn.ibm.com  
  8  k145n36  9.114.133.36  k145n36.kgn.ibm.com  
  9  k145n37  9.114.133.37  k145n37.kgn.ibm.com  
  10  k145n38  9.114.133.38  k145n38.kgn.ibm.com 
  11  k145n39  9.114.133.39  k145n39.kgn.ibm.com 
  12  k145n40  9.114.133.40  k145n40.kgn.ibm.com 
  13  k145n41  9.114.133.41  k145n41.kgn.ibm.com 
  14  k145n42  9.114.133.42  k145n42.kgn.ibm.com 
  15  k145n43  9.114.133.43  k145n43.kgn.ibm.com 
  16  k145n44  9.114.133.44  k145n44.kgn.ibm.com 
  17  k145n45  9.114.133.45  k145n45.kgn.ibm.com 
  18  k145n46  9.114.133.46  k145n46.kgn.ibm.com 
                                                   
Cluster nodes that are not assigned to a nodeset:  
-------------------------------------------------  
  19  k145n47  9.114.133.47  k145n47.kgn.ibm.com 
                                                   
 

See also

mmaddcluster Command

mmcrcluster Command

mmdelcluster Command

mmlscluster Command

Location

/usr/lpp/mmfs/bin