Dell PowerVault ME5 Series Administrator's Guide

Cache optimization mode

You can change the cache optimization mode to one of the following modes of operation.

• standard—In this mode of operation, the controller sets volume cache parameters to address both sequential I/O and random I/O tasks. This optimization is the choice for most workloads. In this mode, the cache is kept coherent with the partner controller. This mode provides high performance and high redundancy, and it is the default.
• cache-hit—This controller cache mode of operation is optimized for workloads that are localized, that is, a substantial percentage of all accesses are hits in the controller cache. In this mode, the cache is kept coherent with the partner controller.
• standard-atomic-write—This controller cache mode of operation adds the atomic-write feature to the standard mode. Atomic Write guarantees that when a Host Write is interrupted for any reason, the data returned on subsequent read will be either the "old" data accepted prior to the interrupted Write or the "new" data from the interrupted write.
• cache-hit-atomic-write—This controller cache mode of operation adds the atomic-write feature to the cache-hit mode. Atomic Write guarantees that when a Host Write is interrupted for any reason, the data returned on subsequent read will be either the "old" data accepted prior to the interrupted Write or the "new" data from the interrupted write.