Robert A Rees

US Patent:

7124131, Oct 17, 2006

Filed:

Apr 29, 2003

Appl. No.:

10/427035

Inventors:

D. Scott Guthridge - Portland OR, US
Rajagopal Ananthanarayanan - Milpitas CA, US
Ralph A. Becker-Szendy - Los Gatos CA, US
Robert M. Rees - Los Gatos CA, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 7/00
G06F 12/00
G06F 15/16

US Classification:

707 8, 707201, 709203

Abstract:

A method and system for asserting a lock in a distributed file system is provided. All distributed locks have a lease for a limited time period, wherein the lease may be renewed periodically. A lock manager data structure is provided to maintain mode compatibility of locks granted to different client nodes for the same object. The process of acquiring or reasserting a lock includes determining whether there are other valid locks in use, as well as whether a valid lock is in operation in a conflicting or compatible mode with a requested lock. A new lock lease may be granted and a lock lease which has expired may be reasserted if a conflicting lease is not present.

US Patent:

7139781, Nov 21, 2006

Filed:

Apr 29, 2003

Appl. No.:

10/427391

Inventors:

Jason C. Young - Portland OR, US
Rajagopal Ananthanarayanan - Milpitas CA, US
Randal C. Burns - Washington DC, US
Darrell D. E. Long - Soquel CA, US
Robert M. Rees - Los Gatos CA, US
Ralph A. Becker-Szendy - Los Gatos CA, US
James J. Seeger - Portland OR, US
David M. Wolfe - Portland OR, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00
G06F 17/30

US Classification:

707204, 707202, 707203

Abstract:

A system and method for managing logical versions of a filesystem made through a near-instantaneous copy process is provided. Each logical version of the filesystem, including the primary version, is assigned a unique epoch number or other identifying value, and each filesystem object is assigned two epoch numbers that define the space of logical versions for which the object exists. A list of all valid epoch numbers are maintained in a version table. The near-instantaneous creation of a logical version of the filesystem requires inserting a unique epoch number entry in the version table () and the next epoch number to the new logical version. An original state of the system is preserved through the use of a copy-on-write procedure for filesystem objects that are reference by that logical filesystem version (). Accordingly, filesystem versions are maintained and original states of previous states of the logical filesystem versions are preserved.

US Patent:

8074041, Dec 6, 2011

Filed:

Dec 9, 2004

Appl. No.:

11/008316

Inventors:

Thomas Keith Clark - Gresham OR, US
Ramakrishna Dwivedula - San Jose CA, US
Roger C. Raphael - San Jose CA, US
Robert Michael Rees - Los Gatos CA, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F 12/00
G06F 13/00
G06F 13/28
G06F 9/26
G06F 9/34
G06F 15/16
G06F 17/30

US Classification:

711170, 711147, 711153, 711204, 709203, 709217, 709229, 707821

Abstract:

An apparatus, system, and method are disclosed for managing storage space allocation. The apparatus includes a recognizing module, a reserving module, and a managing module. The recognizing module recognizes a trigger event at a client of the data storage system. The reserving module reserves logical units of space for data storage. The management module manages the logical units of space at the client. Such an arrangement provides for distributed management of storage space allocation within a storage area network (SAN). Facilitating client management of the logical units of space in this manner may reduce the number of required metadata transactions between the client and a metadata server and may increase performance of the SAN file system. Reducing metadata transactions effectively lowers network overhead, while increasing data throughput.

US Patent:

20050132154, Jun 16, 2005

Filed:

Oct 3, 2003

Appl. No.:

10/678858

Inventors:

Sudhir Rao - Beaverton OR, US
Robert Rees - Los Gatos CA, US
Randal Burns - Washington DC, US
Darrell Long - Soquel CA, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G06F012/00
G06F015/16
G06F013/00

US Classification:

711162000, 709201000

Abstract:

A method and system for election of a cluster leader in a storage area network is provided Each node in a grouping of storage area network nodes communicates with each of the nodes on a periodic basis to determine if any of the nodes have failed (). In the event of a cluster fault, each node may request a position of cluster leader. A pruning protocol () is invoked to ensure efficient convergence of a single cluster leader candidate to favor a majority grouping leader candidate to become the new cluster leader. In the event the leader candidate from the majority grouping has failed to become the new cluster leader, a minority grouping leader candidate can become the cluster leader. Following the pruning protocol, a voting protocol () is invoked followed by lock of the quorum disk () by the elected cluster leader candidate.