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
  • activate-on-create: Snapshots are not activated at creation time by default. If you want created snapshots to immediately be activated after creation, set the activate-on-create parameter to enabled. Note that all volumes are affected by this setting.
  • 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
activate-on-create : 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>]) | ([activate-on-create <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 enables or disables the auto-delete feature. By default auto-delete is disabled.
    • activate-on-create: This enables or disables the activate-on-create feature for all volumes. By default activate-on-create 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