GPFS: Administration and Programming Reference - IRA Home

mmfsctl Command
Name
mmfsctl – Issues a file system control request.
Synopsis
mmfsctl Device {suspend | resume}
Or,
mmfsctl Device {exclude | include} {-d ″DiskName[;DiskName...]″ | -F DiskFile | -G FailureGroup}
Or,
mmfsctl Device syncFSconfig {-n RemoteNodesFile | -C remoteClusterName} [-S SpecFile]
Description
Use the mmfsctl command to issue control requests to a particular GPFS file system. The command is
used to temporarily suspend the processing of all application I/O requests, and later resume them, as well
as to synchronize the file system’s configuration state between peer clusters in disaster recovery
environments.
See Establishing disaster recovery for your GPFS cluster in General Parallel File System: Advanced
Administration Guide.
Before creating a FlashCopy ®
image of the file system, the user must run mmfsctl suspend to
temporarily quiesce all file system activity and flush the internal buffers on all nodes that mount this file
system. The on-disk metadata will be brought to a consistent state, which provides for the integrity of the
FlashCopy snapshot. If a request to the file system is issued by the application after the invocation of this
command, GPFS suspends this request indefinitely, or until the user issues mmfsctl resume.
Once the FlashCopy image has been taken, the mmfsctl resume command can be issued to resume the
normal operation and complete any pending I/O requests.
The mmfsctl syncFSconfig command extracts the file system’s related information from the local GPFS
configuration data, transfers this data to one of the nodes in the peer cluster, and attempts to import it
there.
Once the GPFS file system has been defined in the primary cluster, users run this command to import the
configuration of this file system into the peer recovery cluster. After producing a FlashCopy image of the
file system and propagating it to the peer cluster using Peer-to-Peer Remote Copy (PPRC), users similarly
run this command to propagate any relevant configuration changes made in the cluster after the previous
snapshot.
The primary cluster configuration server of the peer cluster must be available and accessible using remote
shell and remote copy at the time of the invocation of the mmfsctl syncFSconfig command. Also, the
peer GPFS clusters should be defined to use the same remote shell and remote copy mechanism, and
they must be set up to allow nodes in peer clusters to communicate without the use of a password.
Not all administrative actions performed on the file system necessitate this type of resynchronization. It is
required only for those actions that modify the file system information maintained in the local GPFS
configuration data, which includes:
v Additions, removals, and replacements of disks (commands mmadddisk, mmdeldisk, mmrpldisk)
Chapter 8. GPFS commands 181