GPFS: Administration and Programming Reference - IRA Home

mmchnsd Command
Name
mmchnsd – Changes Network Shared Disk (NSD) configuration parameters.
Synopsis
mmchnsd {″DiskDesc[;DiskDesc...]″ | -F DescFile}
Description
The mmchnsd command serves several purposes:
1. Change either or both the primary and backup NSD server nodes.
2. Define a backup server node for an NSD that currently does not have one.
3. Delete a backup server node for an NSD.
4. Delete both the primary and backup NSD server nodes. The disk must now be SAN-attached to all
nodes in the cluster.
5. Assign a primary and, if specified, a backup NSD server node. Nodes that are not SAN-attached to the
disk, or nodes that experience a local device driver failure, will now have access to the data over the
network from these servers.
You must follow these rules when changing NSDs:
v You must identify the disks by the NSD names that were given to them by the mmcrnsd command.
v You must explicitly specify values for both the primary and backup NSD server nodes even if you are
only changing one of them.
v The file system that contains the NSD being changed must be unmounted prior to issuing the
mmchnsd command.
v The NSD must be properly connected to the new nodes prior to issuing the mmchnsd command.
v This command cannot be used to change the DiskUsage or FailureGroup for an NSD. You must issue
the mmchdisk command to change these.
v To move a disk from one storage pool to another, use the mmdeldisk and mmadddisk commands.
v You cannot change the name of the NSD.
Parameters
DiskDesc
A descriptor for each NSD to be changed. Each descriptor is separated by a semicolon (;). The
entire list must be enclosed in single or double quotation marks.
DescFile
Specifies a file containing a list of disk descriptors, one per line.
Each disk descriptor must be specified in the form:
DiskName:PrimaryServer:BackupServer
DiskName
The NSD name that was given to the disk by the mmcrnsd command.
PrimaryServer
The name of the primary NSD server node.
If this field is omitted, the disk is assumed to be SAN-attached to all nodes in the cluster.
To change only the primary NSD server, ensure that if a backup NSD server exists that
you specify it, or the backup NSD server will be deleted. Any parameter that is not
specified defaults to null.
Chapter 8. GPFS commands 109