International Business Machines Corporation

Vikram Harakere Krishnamurthy

Prasenjit Sarkar

Philip Anthony Richardson

Shah Mohammed Rezaul Islam

David Carroll Challener

Richard Christopher Fore

Luis Rene Quinones

Shah Mohammed Islam

A method, system and computer program product for performing an expansion of a disk array. Upon the failure of a disk in the disk array, the failed disk may be rebuilt stripe by stripe in the spare units distributed among other disks in the disk array. Upon repairing or replacing the failed disk with a spare disk, the repaired or spare disk may be rebuilt stripe by stripe using the data from the spare units. Upon receiving a write request to a stripe unit that has been rebuilt in the repaired or spare disk during expansion, the data of the request may be written in the stripe unit requested. Further, the data written may be mirrored, i.e., copied and stored, in the spare unit corresponding to the stripe unit requested. By mirroring the data to the corresponding spare unit, tracking each stripe that was updated during expansion may be eliminated.

Partial mirroring during expansion thereby eliminating the need to track the progress of stripes updated during expansion

A computer-implemented method for managing data snapshots among storage volumes to facilitate transitive, distributed snapshot operations such that a read request or write request can be made to any volume in a snapshot includes establishing respective snapshot tables for the volumes. Each table can correlate, for each chunk of data, a source volume and a target volume. In response to a read request for chunks in one the volumes, the respective snapshot table is accessed, and the read directed to the source volume indicated in the snapshot table. Likewise, in response to a write request for chunks in a storage volume, the table associated with the volume is accessed, and the write is directed to the target volume indicated in the table. For each chunk, the source volume is the same across all tables, such that a read or write involves no more than a single storage volume.

System and method for concurrent distributed snapshot management

A data processing system and method manage usage metadata nodes about data snapshots of data write operations among storage volumes of the system while conserving metadata nodes. Metadata sublogging is achieved by dividing metadata segments into subsegments and tracking them by use of a bitmap.

System for conserving metadata about data snapshots

A method, apparatus, and program product applicable within a multi-drive data storage system for adaptively allocating data reconstruction resources. In accordance with the method of the present invention, responsive to a detected drive failure, a resource allocation manager periodically determines the number of pending host system processing requests. The determined number of pending host system processing requests is then compared to a predetermined threshold value. Finally, a number of processing resources are allocated to data reconstruction in accordance with the results of the comparison of the number of pending host system processing requests to the predetermined threshold.

Adaptive resource allocation in multi-drive arrays

The present invention provides a method and system for more efficiently providing a copy of a portion of a source drive of a plurality of drives in a redundant array of inexpensive disks (RAID) data storage system. The portion of the source drive includes a plurality of segments. The method and system include providing the copy of the plurality of segments from the source drive to the target drive. The plurality of segments can be modified during the step of providing the copy. The method and system further include providing another copy of a portion of the plurality of segments that have been modified since the step of providing the copy commenced if a portion of the plurality of segments have been modified since copying commenced.

Method and system for more efficiently providing a copy in a raid data storage system

A method and system for providing a backup of a portion of a source drive of a plurality of drives in a redundant array of inexpensive disks (RAID) data storage system is disclosed. The portion of the source includes a plurality of segments. The method and system include associating the source drive with a target drive of the plurality of drives and providing a copy of the plurality of segments on the target drive. The copy is provided such that input to and output from source drive and the target drive are allowed during the step of providing the copy of the plurality of segments.

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Durham, NC, United States of America

Vikram Harakere Krishnamurthy