Patent ID: 8131682

Claim:
A method for migrating data from a first storage system to a second storage system, wherein the data is stored as objects, wherein each object is made up of content and metadata, and wherein each object is stored according to a unique object ID (identifier) calculated based upon the content, the method comprising: receiving, in the second storage system, a list of object IDs of objects stored in the first storage system; retrieving, by the second storage system, an object from the first storage system by designating the object ID; calculating, by the second storage system, a new object ID for the retrieved object based upon the content of the object retrieved; storing the content and metadata for the object retrieved in the second storage system; repeating the retrieving, calculating and storing steps for each object in said list until all objects in said list are migrated from the first storage system to the second storage system, wherein the first storage system and the second storage system are contents addressable storage systems, and the object ID identifies a content address of the object without regard to physical location of the data associated therewith; stopping an application program on a host computer prior to migrating the data; installing an application interface program on the host computer for use in interfacing with the second storage system prior to restarting the application program; and placing the second storage system into communication with the host computer; wherein, when the second storage system receives a read request for an object, the second storage system determines whether the object is stored in the second storage system or in the first storage system; wherein when the object is stored in the first storage system, the second storage system: retrieves the object from the first storage system; calculates a new object ID for the retrieved object based upon the content of the retrieved object; stores the content and metadata for the retrieved object in the second storage system; and returns the object and the new object ID in response to the request.