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

Changing your GPFS nodeset configuration

Once your GPFS nodeset has been configured you may be able to tune your nodeset for better performance by reconfiguring one or more attributes. Before you change any attributes, consider how the changes will affect the operation of GPFS. For a detailed discussion see the IBM General Parallel File System for AIX: Concepts, Planning, and Installation Guide and the mmconfig command.

Table 1 details the GPFS nodeset configuration attributes which can be changed by issuing the mmchconfig command. Variations under which these changes take effect are noted:

1. Take effect immediately and are permanent (-i).
2. Take effect immediately but do not persist when GPFS is restarted (-I).
3. Require that the GPFS daemon must be stopped on all nodes for the change to take effect.
4. May be applied to multiple nodes in a list.
5. May require the nodes to reboot or the GPFS daemon to restart.

Table 1. Configuration attributes on the mmchconfig command

	-i option allowed	-I option allowed	GPFS must be stopped on all nodes	list of NodeNames allowed	change takes effect
starting GPFS automatically (autoload)	no	no	no	no	on reboot of the nodes
path for the storage of dumps (dataStructureDump)	yes	yes	no	yes	if not immediately, upon restart of the daemon
node use designation (designation)	no	no	no	yes	restart of the daemon
DMAPI attribute dmapiEventTimeout	yes	yes	no	yes	if not immediately, upon restart of the daemon
DMAPI attribute dmapiMountTimeout	yes	yes	no	yes	if not immediately, upon restart of the daemon
DMAPI attribute dmapiSessionFailureTimeout	yes	yes	no	yes	if not immediately, upon restart of the daemon
maximum file system block size allowed (maxblocksize)	yes	yes	no	yes	if not immediately, upon restart of the daemon
number of inodes to cache for recently used files (maxFilesToCache)	no	no	no	yes	restart of the daemon
number of inodes to keep in stat cache (maxStatCache)	no	no	no	yes	restart of the daemon
size of cache on each node (pagepool)	yes	yes	no	yes	if not immediately, upon restart of the daemon
update how the configuration information is stored (release)	no	no	no	no	immediately
quorum (singleNodeQuorum)	no	no	yes	no	restart of the daemon

Specify the nodes you wish to target for change and the attributes with their new values on the mmchconfig command. For example, to change the pagepool value for each node in the GPFS nodeset set1 immediately, enter:

mmchconfig pagepool=60M -C set1 -i

The system displays information similar to:

mmchconfig: Command successfully completed 
mmchconfig: 6027-1371 Propagating the changes to all affected nodes.
This is an asynchronous process.

See the mmchconfig Command for complete usage information.