A system and method are described to improve the efficiency of copy-on-write operations in a storage system. A partition mapping table is maintained in a cache memory, where the partition mapping table is used to translate logical partitions into physical partitions. A request is received to write one or more blocks BB to a partition PSS, and, upon receiving the request, the pointers in the partition mapping table are interchanged such that data associated with PSS is now associated with a second partition PTT. Next, block(s) BB is written to PSS and an indication is made on the PDSS descriptor that all other data blocks in the partition PSS are invalid.