Patent ID: 6996674

Claim:
A method of maintaining cache in a clustered environment comprising: (a) receiving an I/O request, for modifying data, in a primary node of a storage cluster of two or more nodes; (b) storing die modified data in cache of the primary node; (c) selecting a secondary node for storing the modified data in the secondary node's cache based on a historic point of access list maintained in a cache directory, wherein; (i) the historic point of access list identifies which node's cache contains which data; (ii) the historic point of access indicates that the data is not currently in cache of any node of the storage cluster; and (iii) die secondary node selected is any node in the storage cluster; (d) forwarding the modified data and symbolic information to one or more relevant nodes in the storage cluster, wherein the symbolic information identifies the primary and secondary nodes as containing the modified data; and (e) updating the historic point of access list based on the symbolic information.