System and method for improving the performance of operations requiring parity reads in a storage array system
AssigneeInternational Business Machines Corporation
InventorsJeffrey R. Hartline, James Lee Hafner, Tapas Kanungo
Life of this patent
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Abstract
A system for improving a performance of a write process in an exemplary RAID system reduces a number of IOs required for a short write in a RAID algorithm by using a replicated-parity drive. Parity is stored on the parity portion of the disk drives. A replicated-parity drive comprises all the parity information. Parity information for each parity drive is co-located or mirrored on the replicated-parity portion of the disk drives for fast access during a read portion of the read-modify-write process. Consequently, the system accesses parity data with one seek, as opposed to P seeks in a conventional disk array system utilizing P parity drives.
Claims12
A method of improving read performance of a plurality of parity storage devices during an operation in a storage system, comprising:
- selecting one or more parity storage devices;
- designating each selected parity storage device as a replicated-parity device;
- writing a plurality of data elements and a plurality of parity elements to a stripe in the storage system;
- for each replicated-parity storage device, replicating the parity elements in the stripe to form a plurality of mirrored parity elements on the replicated-parity device;
- associating the replicated-parity device with the stripe;
- reading the mirrored parity elements from the replicated-parity device during the operation, using one IO access to the replicated-parity device;
- and
- rotating permuted stripes within the storage system with respect to a preceding permuted stripe, wherein the rotating comprises aligning at least some of the data elements with the parity elements, and further aligning at least some of the data elements with the mirrored parity elements.
A method of improving read performance of parity portions of a plurality of storage device during an operation, comprising:
- selecting at least some of the parity portions;
- designating each selected parity portion as a replicated-parity portion;
- writing a plurality of data elements and a plurality of parity elements to a stripe in a plurality of storage devices;
- for each replicated-parity portion, replicating the parity elements in the stripe to form a plurality of mirrored parity elements on the replicated-parity portion;
- associating the replicated-parity portion with the stripe;
- reading the mirrored parity elements from the replicated-parity portion during the operation, using one IO access to the replicated-parity portion;
- and
- rotating permuted stripes within the storage system with respect to a preceding permuted stripe, wherein the rotating comprises aligning at least some of the data elements with the parity elements, and further aligning at least some of the data elements with the mirrored parity elements.
Dependencies are inferred from the claim text.