mmpsnap command

Creates or deletes identical snapshots on the cache and home clusters, or shows the status of snapshots that have been queued up on the gateway nodes.

Synopsis

mmpsnap Device create -j FilesetName [[--comment Comment] {[--uid ClusterUID] | --rpo}] [--wait]

or

mmpsnap Device delete -s SnapshotName -j FilesetName

or

mmpsnap Device status -j FilesetName

Availability

Available on all IBM Spectrum Scale editions. Available on AIX® and Linux.

Description

The mmpsnap command creates or deletes identical snapshots on the cache and home clusters, or shows the status of snapshots that have been queued up on the gateway nodes. You can use this command only in a Single writer (SW) cache. You cannot use for Read only (RO), Independent writer (IW), or Local updates (LU) caches. Peer snapshots are not allowed on a Single writer (SW) cache that uses the NSD protocol for communicating with home.

Parameters

Device
Specifies the device name of the file system.
create
Creates a fileset level snapshot in cache and a snapshot with the same name at home. The snapshot at home could be fileset level or file system level, depending on whether the exported path is an independent fileset or file system.
-j FilesetName
Specifies the name of the fileset.
--comment Comment
Optional; specifies user-defined text to be prepended to the snapshot name (thereby customizing the name of the snapshot).
Note: You must use alphanumeric characters when you customize the snapshot name.
--uid ClusterUID
Optional; specifies a unique identifier for the cache site. If not specified, this defaults to the GPFS cluster ID.
--rpo
Optional; specifies that user recovery point objective (RPO) snapshots are to be created for a primary fileset. This option cannot be specified with the --uid option.
--wait
Optional; makes the creation of cache and home snapshots a synchronous process. When specified, mmpsnap does not return until the snapshot is created on the home cluster. When not specified, mmpsnap is asynchronous and returns immediately rather than waiting for the snapshot to be created at home.
delete
Deletes the local and remote copies of the specified snapshot; AFM automatically figures out the remote device and fileset.
-s SnapshotName
Specifies the name of the snapshot to be deleted. A snapshot name is constructed as follows: 
{commentString}-psnap-{clusterId}-{fsUID}-{fsetID}-{timestamp}
Where timestamp has the form YY-MM-DD-HH-MM-SS.
In the following example, a comment string was not provided:
 psnap-14133737607146558608-C0A8AA04:4EDD34DF-1-11-12-05-14-32-10
status
Shows the status of snapshots that have been queued up on the gateway nodes. The status includes the following pieces of information:
  • Last successful snapshot (obtained through mmlsfileset –-afm)
  • Status of the current snapshot process.

Exit status

0
Successful completion.
nonzero
A failure has occurred.

Security

You must have root authority to run the mmpsnap command.

The node on which the command is issued must be able to execute remote shell commands on any other node in the cluster without the use of a password and without producing any extraneous messages. For more information, see Requirements for administering a GPFS file system.

Examples

  1. To create a fileset level snapshot in cache of a single-writer fileset called sw in file system fs1 issue this command:
    mmpsnap fs1 create -j sw
    The system displays output similar to the following:
    Writing dirty data to disk.
Quiescing all file system operations.
Writing dirty data to disk again.
Snapshot psnap-13882361812785649740-C0A80E85:4F44B305-59-12-03-01-02-27-28 created with id 8.
Snapshot psnap-13882361812785649740-C0A80E85:4F44B305-59-12-03-01-02-27-28 created at the satellite.
 Core snapshot has been queued.
  2. To display the snapshot issue this command:
    mmlssnapshot fs1 -j sw
    The system displays output similar to the following:
    Snapshots in file system fs1:
Directory SnapId Status Created Fileset
psnap-13882361812785649740-C0A80E85:4F44B305-59-12-03-01-02-27-28 8 Valid Thu Mar 1 02:27:29 2012 sw
  3. To show that the snapshot is also created at home, issue this command:
    mmlssnapshot fs1
    The system displays output similar to the following:
    Snapshots in file system fs1:
Directory SnapId Status Created Fileset
psnap-13882361812785649740-C0A80E85:4F44B305-59-12-03-01-02-27-28 8 Valid Thu Mar 1 02:23:16 2012

See also

Location

/usr/lpp/mmfs/bin

Parent topic: Command reference