mmlssnapshot command
Displays GPFS™ snapshot information.
Synopsis
mmlssnapshot Device [-d [--block-size {BlockSize | auto}]]
[-s {all | global | [[Fileset]:]Snapshot[,[[Fileset]:]Snapshot...]} | -j Fileset[,Fileset...]]
[--qos QOSClass]
Availability
Available on all IBM Spectrum Scale™ editions.
Description
Use the mmlssnapshot command to display GPFS snapshot information for the specified file system or fileset. You can optionally display the amount of storage that is used by the snapshot.
Parameters
- Device
- The device name of the file system for which snapshot information is to be displayed. File system names do not need to be fully qualified. fs0 is as acceptable as /dev/fs0.
- -d
- Displays the amount of storage that is used by the snapshot.
This operation requires an amount of time that is proportional to the size of the file system; therefore, it can take several minutes or even hours on a large and heavily-loaded file system.
This optional parameter can impact overall system performance. Avoid running the mmlssnapshot command with this parameter frequently or during periods of high file system activity.
- --block-size {BlockSize | auto}
- Specifies the unit in which the number of blocks is displayed. The value must be of the form [n]K, [n]M, [n]G or [n]T, where n is an optional integer in the range 1 - 1023. The default is 1 K. If auto is specified, the number of blocks is automatically scaled to an easy-to-read value.
- -s
- Displays the attributes for the specified snapshots.
- all
- Displays information for all snapshots. This option is the default.
- global
- Displays information for global snapshots.
- [[Fileset]:]
-
- :
- A colon (:) followed by a snapshot name indicates a global snapshot. For example, :SS01 indicates a global snapshot with the name SS01. If a global snapshot with that name exists, the command displays information about it.
- Fileset:
- A fileset name followed by a colon (:) followed by a snapshot name indicates a fileset snapshot. For example, fset02:SS01 indicates a snapshot of fileset fset02 with the name SS01. If a snapshot of the fileset with that snapshot name exists, then the command displays information about it.
- Snapshot[,Snapshot...]
- Displays information for the specified snapshots.
- -j Fileset[,Fileset...]
- Displays only snapshots that contain the specified filesets; including all global snapshots.
- --qos QOSClass
- Specifies the Quality of Service for I/O operations (QoS) class
to which the instance of the command is assigned. If you do not specify
this parameter, the instance of the command is assigned by default
to the maintenance QoS class. This parameter has
no effect unless the QoS service
is enabled. For more information, see the topic mmchqos
command in the IBM
Spectrum Scale: Administration
and Programming Reference. Specify
one of the following QoS classes:
- maintenance
- This QoS class is typically configured to have a smaller share of file system IOPS. Use this class for I/O-intensive, potentially long-running GPFS commands, so that they contribute less to reducing overall file system performance.
- other
- This QoS class is typically configured to have a larger share of file system IOPS. Use this class for administration commands that are not I/O-intensive.
Exit status
- 0
- Successful completion.
- nonzero
- A failure occurred.
Security
You must be a root user or fileset owner to use the -d parameter.
If you are a root user, 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 file system in IBM Spectrum Scale: Administration and Programming Reference.
If you are a non-root user, you can specify only file systems that belong to the same cluster as the node on which the mmlssnapshot command was issued.
Examples
mmlssnapshot fs1
The
following command displays information about snapshots named SS01.
The snapshots can be global snapshots or fileset snapshots:mmlssnapshot fs1 -s SS01
The
following command displays information about a global snapshot named gSS01:mmlssnapshot fs1 -s :gSS01
A
snapshot name can contain a colon (:). The following command displays
information about a global snapshot named :gSS04:mmlssnapshot fs1 -s ::gSS04
The
following command displays information about a fileset snapshot with
the name fsSS01 that is a snapshot of fileset fset02:mmlssnapshot fs1 -s fset02:fsSS01
The
following command displays information about global snapshots with
the names gSS01 and gSS02 and
a fileset snapshot of fileset fset02 named fsSS02:mmlssnapshot fs1 -s :gSS01,:gSS02,fset02:fsSS02
The
following command displays information about global snapshots and
fileset snapshots that contain the filesets fset02 and fset03:mmlssnapshot fs1 -j fset02,fset03