Patent ID: 7627873

Claim:
In a data storage environment having a server, a first and second data storage volume, and production data being stored on the first data storage volume on a first data storage system, and a copy of the data denominated as the data copy being stored on the second data storage volume of a second data storage system, a method of handling Input/Output (IO)-Requests from the server to update the production data so that the data copy is consistent with the production data after processing the IO-Request, the method comprising the steps of: (a) inserting on the first data storage system a first device object above a second device object and a third device object below the second device object to form a stack of layered device objects, wherein the first device object and the third device object are associated with a first device driver and the second device object is associated with a second device driver; (b) the first device driver passing an IO-Request for the production copy on the first data storage system to the first device object; (c) the second device driver associated with the second device object intercepting the and transmitting the IO-Request associated with the first device object to the third device object and to a fourth device object associated with the second device driver on the second data storage system; (d) the second device driver associated with the fourth device object receiving and processing the associated IO-Request for the data copy on the second data storage system; and (e) the first device driver associated with the third device object receiving and processing the associated IO-Request for the production copy on the first data storage system such that when each IO-Request is processed the data on the data copy and the production data are consistent.