International Business Machines Corporation

Veera W Deenadhayalan

James Christopher Wyllie

Steven Robert Hetzler

Robert Michael Rees

James Lee Hafner

Mario Blaum

Pin Zhou

Wayne Curtis Hineman

D Scott Guthridge

Ralph Attila Becker-Szendy

Wendy Ann Belluomini

Parthiban Munusamy

Mark A Johnson

Anurag Sharma

Krishnakumar Rao Surugucchi

Leo Shyh-Wei Luan

Mohan Babu Rowlands

Zhenxing Han

Michael T Roble

Carlos Querol

A computer-implemented method according to one embodiment includes initiating a read-modify-write (RMW) operation; assigning the RMW operation to a thread; identifying a storage device associated with the RMW operation; assign a log block within the storage device to the thread; determining a free shadow block location within the storage device; creating a copy of data to be written to the storage device during the RMW operation; writing the copy of the data to the free shadow block location within the storage device; updating the log block within the storage device to point to the free shadow block location to which the copy of the data is written; and writing the data to one or more blocks of a home area of the storage device.

Optimizing read-modify-write operations to a storage device by writing a copy of the write data to a shadow block

A computer-implemented method includes encoding an array of (p&#x2212;1)&#xd7;k symbols of data into a p&#xd7;(k+r) array. The method includes p is a prime number, r&#x2265;1, and k&#x2264;p&#x2212;r. The method also includes each column in the p&#xd7;(k+r) array has an even parity and each line of slope j for 0&#x2264;j&#x2264;r&#x2212;1 in the p&#xd7;(k+r) array has an even parity. The method includes the lines of slope j taken with a toroidal topology modulo p. A computer program product for encoding an array of (p&#x2212;1)&#xd7;k symbols of data into a p&#xd7;(k+r) array includes a computer readable storage medium having program instructions executable by a computer. The program instructions cause the computer to perform the foregoing method.

Expansion for Blaum-Roth codes

Embodiments of the invention relate to receiving a write request that includes a write data and an address of a target block in tertiary storage. In response to the write request, a write-miss is detected at a cache located in persistent storage. Based on detecting the write-miss, the write data and associated metadata are written to a fast write storage location and the write request is marked as complete. In addition, the target block is retrieved from the address in the tertiary storage and stored in the cache. Contents of the fast write storage location are merged with the contents of the target block in the cache.

Fast write and management of persistent cache in a system that includes tertiary storage

Embodiments relate to a computer system for storing data on a time multiplexed redundant array of independent tapes. An aspect includes a memory device that buffers data received by the computer system to be written to a set of tape data storage devices. The data is written to the set of tape data storage devices in blocks that form parity stripes across the set of tape data storage device. Aspects further includes a tape drive that writes data to one of the set of tape data storage devices at a time in a tape-sequential manner and a processor that computes a parity value for each of the parity stripes. The tape drive writes the parity values for each of the parity stripes to a last subset of tapes of the set of tape data storage devices.

Time multiplexed redundant array of independent tapes

Embodiments of the invention provide parity logs for raid systems with variable-capacity media. In one embodiment, a system includes a first set of data storage media devices having variable capacity. The storage devices include a data portion of a parity data set for storing write data being striped to the first. The system further includes a second set of data storage media devices having variable capacity. The second set includes a linear address space of blocks for storing a parity portion of the parity data set. The linear address space is written in a log form. The first and second sets comprise at least one array in a RAID configuration. The system writes the parity portion of the parity data set to the second set, which enables each storage device among the first set to be written to full capacity.

Parity logs for RAID systems with variable capacity media

Embodiments of the invention relate to accessing data that spans multiple storage devices in a storage system. A first index records identifiers of data blocks and their storage locations, and a second index records storage locations. An update request is processed by writing multiple copies of a received data block identifier and the updated data block to storage locations recorded in the second index. A read request is processed by performing a quorum read of the storage locations recorded in the second index to retrieve the updated data blocks. The processing of the read request also includes performing a quorum read of the first index to determine storage locations that contain data blocks to be read as part of processing the read request. The data blocks to be read exclude the updated data blocks.

Accessing data in a storage system

A data validation method comprises associating a validation chunk with one or more data chunks stored on one or more storage mediums. The validation chunk comprises validation information for verifying whether data recorded in a subdivision of the one or more data chunks is lost. A request is received for an operation to be performed on first data stored in a first subdivision of a first data chunk from among said one or more data chunks. One or more portions of the validation information are examined to determine whether the data recorded in said first subdivision is deemed to be lost.

Monitoring lost data in a storage system

This disclosure relates to parity declustered storage device arrays having partition groups. In an exemplary embodiment, the storage system includes a storage device array, such as disk array. Each storage device is divided into partitions. Each partition includes stripe units, such as hundreds or thousands of stripe units in exemplary embodiments. The storage system also includes a physical array controller coupled to the storage device array. In an exemplary embodiment, the array controller includes a partition group lookup table and stores and retrieves data and parity in the storage devices based on the partition group lookup table. In this exemplary embodiment, the array controller also includes a stripe lookup table and/or a log. In an exemplary embodiment, the partition group lookup table and the stripe lookup table take up less memory (e.g., by an order of magnitude) than a single-level stripe map conveying the same information.

Parity declustered storage device array with partition groups

A write error detection mechanism for a computer data disk drive or storage controller writes and then verifies data to detect disk write errors. It allows the heads to be moved to other tracks to do other jobs in the time it takes the disk to rotate from the point the data was written and to return there again so it can be read to verify the write. The data written is temporarily stored in feature table memory outside the disk, so it can be used as in the comparison later when the written data can be read for the verify. In the interim, other write-and-verify and read operations can be pipelined, or multitasked using the same head, even on different tracks.

Efficient method to detect disk write errors

Data validation systems and methods are provided. Data is recorded in N data chunks on one or more storage mediums. A first validation chunk independently associated with said N data chunks comprises first validation information for verifying accuracy of data recorded in said N data chunks. The first validation chunk is associated with a first validation appendix comprising second validation information, wherein the first validation appendix is stored on a first storage medium independent of said one or more storage mediums.

Data integrity validation in storage systems

A system (and method) for determining reconstruction formulas for partial strip reconstruction in a storage system in which a plurality of lost strips have been detected, includes using a combination of a direct reconstruction method and a sequential reconstruction method.

System and method for reconstructing lost data in a storage system

A storage controller and associated disk or disk portion where after the controller terminates its access to said disk or disk portion, data integrity problems in the disk or disk portion can be detected. Before host data associated with a write command is written from the cache memory to the disk or disk portion, an identity of the storage controller as a current user of the disk or disk portion and indication that the controller is operating in a mode it stores data in a cache is recorded on the disk or disk portion. If the storage controller is shut down abnormally, the record of the identity of the controller and the indication are not cleared. The storage controller is restarted or rebooted and the record is read to learn that the controller was using the disk or disk portion and operating in the foregoing mode before the shutdown.

System and method for detecting data integrity problems on a data storage device

A method and device for detecting and handling non-responsive devices in a computer system where the device non-responsiveness may be due to a powered-down status rather than a device failure, and more particularly to such computer systems when the devices are RAID disk drives. By scanning all devices connected in a configuration and maintaining a count of devices that time out without responding, a determination can be made as to whether the devices are powered off or are experiencing some other problem that requires attention of a system support technician.

Growing community of inventors

San Jose, CA, United States of America

Veera W Deenadhayalan