Extended storage capacity for a network file server

Abstract

A NAS switch provides extended storage capacity to a file server in a decentralized storage network such as a NAS (Network Attached Storage) storage network. The NAS switch sits in the data path of a client on the front end and a directory file server and shadow file servers on the back end. A segregation module in the NAS switch replicates data from the directory file server to a shadow file server, and then replaces the data in the directory file server with holey files. Holey files, which store a range of consecutive values such as zero with negligible storage space, retain the attributes of the data without retaining its storage consumption. Thus, the directory file server can server as a single directory hierarchy for several shadow file servers containing data beyond a capacity of the directory file server. When the NAS switch receives operations from the client, an association module forwards directory operations to the directory file server and data operations to the shadow file server. The NAS switch also provides services to several shadow file servers from a single directory file server.