Darrell D Long

US Patent:

20040220979, Nov 4, 2004

Filed:

Apr 29, 2003

Appl. No.:

10/427391

Inventors:

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

International Classification:

G06F012/00

US Classification:

707/203000

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:

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.