GPFS: Administration and Programming Reference - IRA Home

dataAndMetadata
Indicates that the disk contains both data and metadata. This is the default.
dataOnly
Indicates that the disk contains data and does not contain metadata.
metadataOnly
Indicates that the disk contains metadata and does not contain data.
descOnly
Indicates that the disk contains no data and no file metadata. Such a disk is used
solely to keep a copy of the file system descriptor, and can be used as a third
failure group in certain disaster recovery configurations. For more information, see
General Parallel File System: Advanced Administration and search on
Synchronous mirroring utilizing GPFS replication.
FailureGroup
A number identifying the failure group to which this disk belongs. You can specify any
value from -1 (where -1 indicates that the disk has no point of failure in common with any
other disk) to 4000. If you do not specify a failure group, the value defaults to the NSD
primary server node number plus 4000. If an NSD server node is not specified, the value
defaults to -1. GPFS uses this information during data and metadata placement to assure
that no two replicas of the same block are written in such a way as to become unavailable
due to a single failure. All disks that are attached to the same NSD server or adapter
should be placed in the same failure group.
If replication of -m or -r is set to 2 for the file system, storage pools must have two failure
groups for the commands to work properly.
StoragePool
Specifies the storage pool to which the disk is to be assigned. If this name is not provided,
the default is system.
Only the system pool may contain metadataOnly, dataAndMetadata, or descOnly disks.
-F DescFile
Specifies a file containing a list of disk descriptors, one per line. You may use the rewritten
DiskDesc file created by the mmcrnsd command or create your own file. When using the
DiskDesc file created by the mmcrnsd command, the values supplied on input to the command
for Disk Usage and FailureGroup are used. When creating your own file, you must specify these
values or accept the system defaults. A sample file can be found in /usr/lpp/mmfs/samples/
diskdesc.
-N { Node[,Node...] | NodeFile | NodeClass}
Specifies the nodes that are to participate in the restripe of the file system after the specified disks
have been made available for use by GPFS. This parameter can be used only in conjunction with
the -r option. This command supports all defined node classes. The default is all (all nodes in the
GPFS cluster will participate in the restripe of the file system).
Options
For general information on how to specify node names, see “Specifying nodes as input to GPFS
commands” on page 4.
-a Specifies asynchronous processing. If this flag is specified, the mmadddisk command returns
after the file system descriptor is updated and the rebalancing scan is started; it does not wait for
rebalancing to finish. If no rebalancing is requested (the -r flag not specified), this option has no
effect.
-r Rebalance all existing files in the file system to make use of new disks.
mmadddisk Command
Chapter 8. GPFS commands 63