Both the Flash Pool technology and the family of Flash Cache modules (Flash Cache and Flash Cache 2) provide a high-performance cache to increase storage performance. However, there are differences between the two technologies that you should understand before choosing between them.
You can employ both technologies on the same system. However, data stored in volumes associated with a Flash Pool aggregate (or an SSD aggregate) is not cached by Flash Cache.
|Criteria||Flash Pool aggregate||Flash Cache|
|Scope||A specific aggregate||All aggregates assigned to a controller|
|Caching types supported||Read and write||Read|
|Cached data availability during and after takeover events||Cached data is available and unaffected by either planned or unplanned takeover events.||Cached data is not available during takeover events. After giveback for a planned takeover, previously cached data that is still valid is re-cached automatically.|
|PCIe slot on storage controller required?||No||Yes|
|Supported with array LUNs?||No||Yes|
|Supported with Storage Encryption?||No||Yes. Data in the cache is not encrypted.|
|Supported with SnapLock?||No||Yes|
For more information about Flash Cache, see the Data ONTAP System Administration Guide for 7-Mode.