Best Practices for AFM DR

Minimizing data loss during primary failure

AFM DR is asynchronous, so there is always a chance data can be lost in the event of a failure. The amount of data lost is affected by:

The network bandwidth between the primary and secondary.
The performance of the gateway which depends on Spectrum Scale tuning, the amount of memory and CPU available to gateway node and the number of filesets allocated to each gateway node. If the gateway node is overloaded it can result in replication rate reduction and reduced network bandwidth utilization.
The ability of the primary and secondary to read and write the data to disk.

The AFM DR replication should be tuned to minimize the data loss in case of primary failure by keeping-up with the data creation rate. Some workloads occur in bursts, in this case you can design for average data transfer rates though keep in mind the time to sync is much greater right after a burst of changes.

Note: The AFM DR replication rate is independent of the RPO interval. The RPO interval does not affect the data loss sustained during primary failure.

Generating notification for failed replication

There is no automated notification mechanism in AFM DR to monitor the replication rates that are falling behind as long as they are within the RPO. However, a script can be written to periodically test the gateway node to see how fast the message queue is being processed. This provides an estimate of the replication rate sustained by the gateway node.

To monitor the RPO you can use the AFMRPOMISS callback event. This event is triggered if the RPO snapshot is not taken at the set interval. The event indicates something is wrong within the system, and can be used as a trigger to start an analysis of what needs to be rectified within the system to bring it back to optimal performance.

Using tuning parameters to improve performance

There are several AFM DR tuning parameters that can be used to tune performance. For more information on tuning parameters, see Configuration parameters for AFM-based DR.