Data storage system with physical storage and cache memory

A data storage system comprises physical storage, cache memory and a processor connected to the physical storage and the cache memory. The processor is arranged to maintain a set of active regions in the cache memory, each active region having a size equal to an integer multiple of an update size of a flash chip within the physical storage, where the integer could be 1. The processor receives requests for one or more blocks of the cache memory from components within the storage system and allocates one or more blocks from an active region in response to a received request. If the processor determines that all blocks in an active region have been allocated and that all allocated blocks within this region have been written to, then the processor destages the content of this region to the physical storage.