Abstract: 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 T1, a time T1 snapshot volume of a live volume of data in the file system; receive, from a client C1 at a time subsequent to T1, an update access request for a portion of a file that includes data stored in access unit B1 of the live volume subsequent to time T1; and responsive to the update access request, allocate, to the time T1 snapshot volume, a new access unit B2 corresponding to access unit B1, and copy data stored in access unit B1 to access unit B2.

Abstract: 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 T1, a time T1 snapshot volume of a live volume of data in the file system; receive, from a client C1 at a time subsequent to T1, an update access request for a portion of a file that includes data stored in access unit B1 of the live volume subsequent to time T1; and responsive to the update access request, allocate, to the time T1 snapshot volume, a new access unit B2 corresponding to access unit B1, and copy data stored in access unit B1 to access unit B2.

Abstract: 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.