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

Changing the GPFS cluster configuration data

Once your GPFS cluster has been configured (see the IBM General Parallel File System for AIX: Concepts, Planning, and Installation Guide and the mmcrcluster command), you can change configuration attributes by issuing the mmchcluster command:

• Change the primary or secondary GPFS cluster data server nodes. The primary or secondary server may be changed to another node in the GPFS cluster. That node must be available for the command to be successful.
• Synchronize the primary GPFS cluster data server node. 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.
• Change the remote shell and remote file copy programs to be used by the nodes in the cluster. These command must adhere to the syntax forms of rsh and rcp but may implement an alternate authentication mechanism.

Attention: The mmchcluster command is able 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.

For example, to change the primary server for the GPFS cluster data, enter:

mmchcluster -p k145n08   

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:    k145n08.kgn.ibm.com        
  Secondary server:  k145n44.kgn.ibm.com        
                                                   
Nodes in nodeset set1:                                
----------------------                                
  1  k145n29  9.114.133.29  k145n29.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 set2:                              
----------------------                              
  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  k145n08  9.114.133.08  k145n08.kgn.ibm.com
 

See the mmchcluster Command and the mmlscluster Command for complete usage information.