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mmcrnsd Command
Name
mmcrnsd – Creates cluster-wide names for Network Shared Disks (NSDs) used by GPFS.
Synopsis
mmcrnsd -F DescFile [-v {yes |no}]
Description
The mmcrnsd command is used to create cluster-wide names for NSDs used by GPFS.
This is the first GPFS step in preparing a disk for use by a GPFS file system. A disk descriptor file
supplied to this command is rewritten with the new NSD names and that rewritten disk descriptor file can
then be supplied as input to the mmcrfs, mmadddisk or mmrpldisk commands.
The name created by the mmcrnsd command is necessary since disks connected at multiple nodes may
have differing disk device names in /dev on each node. The name uniquely identifies the disk. This
command must be run for all disks that are to be used in GPFS file systems. The mmcrnsd command is
also used to assign a primary and backup NSD server that can be used for I/O operations on behalf of
nodes that do not have direct access to the disk.
To identify that the disk has been processed by the mmcrnsd command, a unique NSD volume ID is
written on sector 2 of the disk. All of the NSD commands (mmcrnsd, mmlsnsd, and mmdelnsd) use this
unique NSD volume ID to identify and process NSDs.
After the NSDs are created, the GPFS cluster data is updated and they are available for use by GPFS.
When using an IBM Eserver High Performance Switch (HPS) in your configuration, it is suggested you
process your disks in two steps:
1. Create virtual shared disks on each physical disk through the mmcrvsd command.
2. Using the rewritten disk descriptors from the mmcrvsd command, create NSDs through the mmcrnsd
command.
Results
Upon successful completion of the mmcrnsd command, these tasks are completed:
v NSDs are created.
v The DescFile contains NSD names to be used as input to the mmcrfs, mmadddisk, or the mmrpldisk
commands.
v A unique NSD volume ID to identify the disk as an NSD has been written on sector 2.
v An entry for each new disk is created in the GPFS cluster data.
Parameters
-F DescFile
The file containing the list of disk descriptors, one per line. Disk descriptors have this format:
DiskName:PrimaryServer:BackupServer:DiskUsage:FailureGroup:DesiredName:StoragePool
DiskName
The block device name appearing in /dev for the disk you want to define as an NSD.
Examples of disks accessible through a block device are SAN-attached disks or virtual
shared disks. If a PrimaryServer node is specified, DiskName must be the /dev name for
the disk device on the primary NSD server node. See the Frequently Asked Questions at
126 GPFS: Administration and Programming Reference