Storage control cache

Certain storage control models, such as IBM's Enterprise Storage Server (ESS) and TotalStorage DS8000 Series, contain a special high-speed (relative to disk) memory known as storage control cache. This cache serves two purposes:

When reading data from disk, if the data is already in the storage control cache, the program can access it directly from the cache without having to wait for the (relatively slow) disk to retrieve it.
When writing data to disk, by writing directly to the cache (through use of cache fast write), applications can complete their write operations significantly faster than if they had written to the disk directly.

DFSORT takes advantage of the storage control cache by writing to its work data sets with cache fast write enabled. This speeds up the time needed to write to these work data sets as well as to read back from them.

To benefit from DFSORT's ability to use cache fast write (CFW), ensure that the CFW feature is activated on your storage control units (if appropriate).

DFSORT also takes advantage of the storage control cache by selecting the appropriate caching mode for input and output data sets. This reduces elapsed time for DFSORT applications and also helps other non-DFSORT applications make better use of the cache.