Patent ID: 7096342

Claim:
A method for facilitating writing and retrieval in a content addressed storage (CAS) system utilizing a Logical Unit Number/Logical Block Address (LUN/LBA) interface comprising steps of: a. receiving an input/output (I/O) operation request, associated application-level LUN/LBA combination, and optionally, content data from an application program at a first LUN/LBA processing tier or at a second OID processing tier, b. hashing said content data to generate an OID at said second OID processing tier if content data is received in said receiving step, c. consulting a high-level OID table and an access property with said received application-level LUN/LBA combination or said generated OID to determine whether said content data can be retrieved from or written to an LUN/LBA combination, respectively, and based on said consulting step, performing at a third storage subsystem LUN/LBA processing tier actions comprising: a write, over-write, or addition operation to an LUN/LBA combination, a retrieval from an LUN/LBA combination, and a denial of operation.