Patent ID: 8156163

Claim:
A network storage system comprising: a plurality of storage controllers; a plurality of storage servers, each implemented in a separate one of the plurality of storage controllers, each of the storage servers configured to present to users a separate system image of stored data; and a storage server cluster including a plurality of cooperating storage server nodes, distributed among said plurality of storage controllers, the storage server cluster configured to present to users a single system image of data stored in the storage server cluster independently of the storage server node or nodes in which said data resides, the storage server cluster being configured to operate concurrently with operation of at least one of the plurality of storage servers, wherein the storage server cluster is configured to operate independently of the plurality of storage servers, wherein the plurality of storage servers separately implement a plurality of distinct file systems, and wherein the storage server nodes of the storage server cluster collectively implement one or more file systems in a single global namespace.