Dell PowerVault ME5 Series Administrator's Guide

Effect of failover on metrics

Controller A is the active metrics server by default. It has the one active metrics database on the storage system. Controller B does not have a metrics database, and simply forwards samples to controller A as they are received from Storage Controller B. This single-metrics database exists in RAM only. It is not redundantly maintained, and is lost if controller A goes offline.

If controller A goes offline, all current metrics samples are lost. Controller B becomes active, creates an empty metrics database on the memory card, and begins storing and persisting samples to cover for controller A. When controller A is back online, controller B clones its current database to controller A. Controller A then initializes its metrics database with the contents of those files.