Patent ID: 8868874

Claim:
A system comprising: an index generator adapted to receive a plurality of requests and generate a plurality of responses for each request, each response containing a sequenced index based on the order in which the request was received; at least two storage systems communicating with each other to store writes received from one or more external systems in a synchronous manner, each storage system adapted to: receive writes from an external system; request an index from the index generator for each write; send the writes to the at least one other storage system; receive writes from the at least one other storage system; receive indexes from the index generator for writes from the at least one other storage system independently of the writes received from the at least one other storage system; store the writes from the external system and the at least one other storage system based on the ordered indexes received from the index generator; and report a completion of the writes received from the external system to the external system after completion of the writes on the at least one other storage system.