8.7. Configuring Snapshot Behavior

The configurable parameters for snapshot are:
  • snap-max-hard-limit: If the snapshot count in a volume reaches this limit then no further snapshot creation is allowed. The range is from 1 to 256. Once this limit is reached you have to remove the snapshots to create further snapshots. This limit can be set for the system or per volume. If both system limit and volume limit is configured then the effective max limit would be the lowest of the two value.
  • snap-max-soft-limit: This is a percentage value. The default value is 90%. This configuration works along with auto-delete feature. If auto-delete is enabled then it will delete the oldest snapshot when snapshot count in a volume crosses this limit. When auto-delete is disabled it will not delete any snapshot, but it will display a warning message to the user.
  • auto-delete: This will enable or disable auto-delete feature. By default auto-delete is disabled. When enabled it will delete the oldest snapshot when snapshot count in a volume crosses the snap-max-soft-limit. When disabled it will not delete any snapshot, but it will display a warning message to the user
  • Displaying the Configuration Values

    To display the existing configuration values for a volume or the entire cluster, run the following command:

    # gluster snapshot config [VOLNAME]
    where:
    • VOLNAME: This is an optional field. The name of the volume for which the configuration values are to be displayed.
    If the volume name is not provided then the configuration values of all the volume is displayed. System configuration details are displayed irrespective of whether the volume name is specified or not.
    For Example:
    # gluster snapshot config
    
    Snapshot System Configuration:
    snap-max-hard-limit : 256
    snap-max-soft-limit : 90%
    auto-delete : disable
    
    Snapshot Volume Configuration:
    
    Volume : test_vol
    snap-max-hard-limit : 256
    Effective snap-max-hard-limit : 256
    Effective snap-max-soft-limit : 230 (90%)
    
    Volume : test_vol1
    snap-max-hard-limit : 256
    Effective snap-max-hard-limit : 256
    Effective snap-max-soft-limit : 230 (90%)
  • Changing the Configuration Values

    To change the existing configuration values, run the following command:

    # gluster snapshot config [VOLNAME] ([snap-max-hard-limit <count>] [snap-max-soft-limit <percent>]) | ([auto-delete <enable|disable>])
    where:
    • VOLNAME: This is an optional field. The name of the volume for which the configuration values are to be changed. If the volume name is not provided, then running the command will set or change the system limit.
    • snap-max-hard-limit: Maximum hard limit for the system or the specified volume.
    • snap-max-soft-limit: Soft limit mark for the system.
    • auto-delete: This will enable or disable auto-delete feature. By default auto-delete is disabled.
    For Example:
    # gluster snapshot config test_vol snap-max-hard-limit 100
    Changing snapshot-max-hard-limit will lead to deletion of snapshots if
    they exceed the new limit.
    Do you want to continue? (y/n) y
    snapshot config: snap-max-hard-limit for test_vol set successfully