Abstract: Nodes in a data storage system having redundant write caches identify when one node fails. A remaining active node stops caching new write operations, and begins flushing cached dirty data. Metadata pertaining to each piece of data flushed from the cache is recorded. Metadata pertaining to new write operations are also recorded a corresponding data flushed immediately when the new write operation involves data in the dirty data cache. When the failed node is restored, the restored node removes all data identified by the metadata from a write cache. Removing such data synchronizes the write cache with all remaining nodes without costly copying operations.

Abstract: An apparatus having one or more memories and a controller is disclosed. The memories are divided into a plurality of regions. Each regions is divided into a plurality of blocks. The blocks correspond to a plurality of memory addresses respectively. The controller is configured to (i) receive data from a host, (ii) generate metadata that maps a plurality of host addresses of the data to the memory addresses of the memories and (iii) write sequentially into a given one of the regions both (a) a portion of the data and (b) a corresponding portion of the metadata.