Patent ID: 7562078

Claim:
A method for retention of active data in a main memory in a storage server comprising: reading data into a first location of the main memory of the storage server, the data in the first location being a data image of data elements in a long-term data storage and the data in the first location indexing the data elements in the long-term data storage in a first manner, the data elements in the storage server being a mirror of data elements in a second storage server; receiving an update for the storage server to mirror a change in the second storage server; in response to receipt of the update for the storage server, copying the data from the first location into a second location in the main memory of the storage server, the data in the second location indexing the data elements in the long-term data storage in a second manner; releasing data in the first location and generating a third location in the main memory for the data, the third location indexing the data elements in the long-term storage in the same manner as the first location; receiving a request for a data element and determining whether the data element is present in the third location in the main memory; if the data element is not present in the third location in the main memory, further comprising determining whether the data element is contained in the second location in the main memory and upon determining that the data element is not contained in the third location and is contained in the second location, further comprising copying the data from the second location to the third location.