Caching with flash-based memory

A system for use in caching with flash-based memory, the system comprising:

• first and second controllers communicating with a flash-based cache, wherein the first controller communicates with a first volatile memory cache and the second controller communicates with a second volatile memory cache;
• and
• a magnetic disk array in communication with the flash-based cache;
• wherein
• the flash-based cache is in communication with the first and second volatile memory caches, wherein the flash-based cache serves as an extension of the first and second volatile memory caches by providing the flash-based cache for caching data in addition to the first and second volatile memory caches, wherein the flash-based cache represents a non-volatile portion of a cache subsystem of the system, wherein the cache subsystem includes the flash-based cache and the first and second volatile memory caches, wherein a write I/O from a host is acknowledged to the host as complete once the data from the write I/O has been copied to the flash based cache;
• the flash-based cache has a dual ported link to the first and second controllers, wherein the dual ported link enables the first and second controllers to simultaneously access memory in the flash-based cache, wherein the dual ported link enables the first controller to continue accessing the memory in the flash-based cache upon failure of the second controller;
• and
• the flash-based cache has flash-based memory components arranged in a RAID data protection scheme.