Displaying and changing the file system manager node

In general, GPFS™ performs the same functions on all nodes. There are also cases where one node provides a more global function that affects the operation of multiple nodes. For example, each file system is assigned a node that functions as a file system manager.

For a more detailed discussion on the role of the file system manager node, see Special management functions.

The node that is the file system manager can also be used for applications. In some cases involving very large clusters or applications that place a high stress on metadata operations, it may be useful to specify which nodes are used as file system managers. Applications that place a high stress on metadata operations are usually those that involve large numbers of very small files, or that do very fine-grain parallel write-sharing among multiple nodes.

You can display the file system manager node by issuing the mmlsmgr command. You can display the information for an individual file system, a list of file systems, or for all of the file systems in the cluster. For example, to display the file system manager for the file system fs1, enter:

mmlsmgr fs1

The output shows the device name of the file system and the file system manager's node number and name:

file system      manager node       [from 19.134.68.69 (k164n05)]
---------------- ------------------
fs1              19.134.68.70 (k164n06)

For complete usage information, see mmlsmgr command.

You can change the file system manager node for an individual file system by issuing the mmchmgr command. For example, to change the file system manager node for the file system fs1 to k145n32, enter:

mmchmgr fs1 k145n32

The output shows the file system manager's node number and name, in parentheses, as recorded in the GPFS cluster data:

GPFS: 6027-628 Sending migrate request to current manager node 19.134.68.69 (k145n30).
GPFS: 6027-629 [N] Node 19.134.68.69 (k145n30) resigned as manager for fs1.
GPFS: 6027-630 [N] Node 19.134.68.70 (k145n32) appointed as manager for fs1.

For complete usage information, see mmchmgr command.