Expiring a disconnected RO cache

Read-only filesets can be configured to expire cached data after the gateway nodes are in a disconnected state for a specified amount of time.

This feature provides control over how long a network outage between the cache and home can be tolerated before the data in the cache is considered stale. This prevents access to old data, where old is defined by the amount of time that the WAN cache is out of synchronization with the data at the home site. Cached data is only available until the time period set in the afmExpirationTimeout parameter expires, at which point the cached data is considered 'expired' and cannot be read until a reconnect occurs.

This feature is not available in other AFM modes.

RO cache filesets that are created by using the NSD protocol do not automatically go to the expired state, even if the expiration timeout is set for them. The RO cache filesets remain in the unmounted state for as long as the home file system is unavailable. The administrator can manually expire the data in an RO cache before the expiration timeout is reached, using the mmafmctl expire command only if the expiration timeout is configured for the fileset. An RO cache that is created by using NSD protocol can also be manually expired. Use the following command:

#mmafmctl Device {resync | expire | unexpire | stop | start} -j FilesetName

For more information, see mmafmctl command.

Expiring an RO fileset -

#  mmafmctl fs1 expire -j ro1

# mmafmctl fs1 getstate -j ro1


          Fileset Name Fileset TargetCache State Gateway Node Queue Length Queue numExec
          ------------ --------------  ---------- ------------ ------------ -------------
          ro1          gpfs:///gpfs/remotefs1/dir1    Expired     c26c4apv1    0        4

Unexpiring an RO fileset -

# mmafmctl fs1 unexpire -j ro1

#mmafmctl fs1 getstate -j ro1


          Fileset Name Fileset Target       Cache State Gateway Node Queue Length  Queue numExec
          ------------ --------------        ----------- ------------ ------------ -------------
          ro1          gpfs:///gpfs/remotefs1/dir1         Active      c26c4apv1    0            4

The afmFilesetExpired callback event is triggered when a fileset moves into expired state. The afmFilesetUnexpired callback event is triggered when a fileset moves out of the expired state.