Dell PowerEdge RAID Controller 12 User’s Guide PERC H965i Adapter, PERC H965i Front, PERC H965i MX, and PERC H965e Adapter

The PERC 12 series of cards contain local DRAM on the controllers. This DRAM can cache I/O operations for improvement of both read and write operations.

I/O workload to HDDs, such as random read-write 512 B and 4 kB, may take some time to flush cached data. Cache is flushed periodically, but for configuration changes or system shutdown, the cache is required to be flushed before the operation can be completed. It can take several minutes to flush cache for some workloads depending on the speed of the HDDs and the size of data in the cache.

The following operations require a complete cache flush:

• Configuration changes (add or delete VDs, VD cache setting changes, foreign configuration scan, and import)
• System restart or shutdown
• Abrupt power loss causing Controller cache preservation.