Data replication method over a limited bandwidth network by mirroring parities

A storage architecture for data mirroring/replication, disk-to-disk backup, archiving, or ILM (information lifecycle management) comprising:

• (a) a network;
• (b) a primary storage system for serving storage requests and storing data blocks, wherein the primary storage system has
• i) a central processing unit (CPU),
• ii) a random access memory (RAM) operatively connected to the CPU and segmented into a parity cache for storing a difference between an old parity and a new parity of each data block until the difference is replicated to a remote site, stored in an archiving storage, or moved to an ILM storage, and
• iii) a parity computation engine for determining the difference;
• and
• (c) a secondary storage system in communication with the primary storage system via the network, wherein the secondary storage system provides data mirroring storage for the primary storage system for data recovery and business continuity, a backup storage, archiving storage, or ILM storage, wherein the secondary storage system stores mirrored copy of data of the primary storage or a delta-parity of changed data blocks for saving storage space,
• wherein the secondary storage system is a disk-to-disk backup and data stored thereon is either directly mirrored from the primary storage system or computed based on the difference when transferred from the primary storage system such that the difference can be used to recompute data back upon retrieval using successive EX-OR functions.

A system for storing data in a network comprising:

• first means for calculating a delta_parity at a primary storage system;
• second means for caching the delta_parity and data at the primary storage system;
• third means for transmitting the delta_parity;
• and
• a secondary storage system for receiving the delta_parity, the secondary storage system being operative to perform the step of computing parity based upon the delta_parity, wherein the secondary storage system being operative to perform the following step of deriving new data based upon the computed parity and data present at the secondary storage system.