Hewlett-packard Development Company, L.P.

Hewlett-packard Company

Lawrence E Rupp

Gary Lee Thunquest

A method for a file server to support snapshots in a storage area network (SAN) providing a plurality of clients with concurrent direct I/O access to a file system in the SAN, in which the SAN uses an access protocol for file system access. The method includes operating the file server to: start to maintain, at a time T, a time Tsnapshot volume of a live volume of data in the file system; receive, from a client Cat a time subsequent to T, an update access request for a portion of a file that includes data stored in access unit Bof the live volume subsequent to time T; and responsive to the update access request, allocate, to the time Tsnapshot volume, a new access unit Bcorresponding to access unit Band copy data stored in access unit Bto access unit B

Method and apparatus for supporting snapshots with direct I/O in a storage area network

A dual process display server comprising a first memory; a second memory; a first process for receiving requests from a client program, dispatching client requests falling within a first prescribed category of requests, storing in the first memory requests falling within a second prescribed category of requests and storing in the second memory messages associated with requests stored in the first memory; and a second process for retrieving messages from the second memory, retrieving client requests from the first memory, and dispatching requests retrieved from the first memory in accordance with messages retrieved from the second memory.

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Loveland, CO, United States of America

Lawrence E Rupp