Emc Corporation

Array Technology, LLC

David W. Gordon

Walter A. Hubis

David C. Stallmo

David M. Warner

William A. Brant

David W Gordon

William A Brant

David C Stallmo

Walter A Hubis

Jeff Samson

Warren Conner

David M Warner

A fault tolerant storage subsystem includes a first tier of failure independent data storage units coupled to a storage controller, and a second tier, including at least one failure independent data storage unit, coupled to at least one of the failure independent data storage units in the first tier for providing further fault tolerance thereto. The first tier of failure independent data storage units may include a partially heterogeneous group of data storage units, which may include a solid state data storage unit. Data blocks representative of data received from the storage controller are stored on at least a first subset of the first tier of failure independent data storage units and associated redundancy blocks representative of redundancy information associates with the data blocks are stored on a second subset of the first tier of failure independent data storage units.

Storage device array architecture with solid-state redundancy unit

A method for on-line restoration of redundancy information in a redundant array storage system. The invention provides alternative methods of restoring valid data to a storage unit after a Write failure caused by a temporary storage unit fault. In the first preferred method, a valid redundancy block is generated for the corresponding data blocks on all storage units. Resubmitting the interrupted Write operation causes the old (and potentially corrupted) data block to be 'subtracted' out of the re-computed redundancy block. The uncorrupted new data block is written over the old data block, and is 'added' into the re-computed redundancy block to create a new, corrected redundancy block. The new, corrected redundancy block is written to the appropriate storage unit. In the second preferred method, a new redundancy block is generated from all valid data blocks and the new data block. The new redundancy block and the new data block are then written to the appropriate storage units. In both cases, the entire method is done on-line, with insignificant interruption of normal operation of the redundant array system, and without requiring added processing during normal operation.

On-line restoration of redundancy information in a redundant array system

A fault-tolerant storage device array using a solid-state storage unit for storage of redundancy information. The invention solves the redundancy bottleneck inherent in a RAID 4 architecture by replacing the electro-mechanical redundancy storage unit with a solid-state device (SSD). The present invention requires reading an old data block from a storage unit and an old redundancy data block from the SSD, then combining the old data block, a new data block, and the old redundancy data block to generate a new redundancy data block, and thereafter writing the new data block to a storage unit and the new redundancy data block to the SSD. However, reading the old redundancy data block from the SSD and writing the new redundancy data block to the SSD at electronic speeds takes a negligible amount of time compared to the Read and Write times of a typical rotating disk storage unit. While the storage unit on which a new data block will be stored is involved for the duration of each data modification operation, the involvement of the SSD in the operation ceases upon writing the new redundancy data block. Thereafter, the SSD is available for updating a redundancy data block for a next storage unit.

A redundant array based data storage system used in computer systems for reducing the amount of time required to modify data records stored in the redundant array. The storage system reduces the number of transmissions between a storage unit within the redundant array and the array controller by incorporating a parity storage unit which is programmed to perform operations necessary to the calculation of a 'parity code' which is used for error detection and correction. By integrating the redundancy information generation into the storage unit used to store the parity information, the number of transmissions between various component parts of the system is reduced, and so the amount of time required to perform a 'read-modify-write' operation is reduced. Disk-type parity units having more than one read/write head are used to further increase the performance of the storage system by reducing the disk rotational latency time.

Storage unit generation of redundancy information in a redundant storage

A method for on-line restoration of redundancy information in a redundant array storage system. The invention provides alternative methods of restoring valid data to a storage unit after a Write failure caused by a temporary storage unit fault. In the first preferred method, a valid redundancy block is generated for the corresponding data blocks on all storage units. Resubmitting the interrupted Write operation causes the old (and potentially corrupted) data block to be 'subtracted' out of the re-computed redundancy block. The uncorrupted new data block is written over the old data block, and is 'added' into the recomputed redundancy block to create a new, corrected redundancy block. The new, corrected redundancy block is written to the appropriate storage unit. In the second preferred method, a new redundancy block is generated from all valid data blocks and the new data block. The new redundancy block and the new data block are then written to the appropriate storage units. In both cases, the entire method is done on-line, with insignificant interruption of normal operation of the redundant array system, and without requiring added processing during normal operation.

Pill crusher

An arrayed disk drive system for providing memory to a computer, said arrayed system having a plurality of disk drives configured to form an array, said arrayed disk drives accessed by a plurality of channels, each channel accessing a plurality of disk drives, including a means for controlling the logical configuration of the arrayed disk drives to appear to the computer as any conceivable arrangement of disk drives, whereby the arrayed disk drive may appear to the computer as the plurality of disk drives, or as one large disk drive comprised of all the arrayed disk drives, or any combination in between. A means for providing a plurality of levels of redundancy on data read or written by the computer to the arrayed disk drives is provided, as well as means controlled by the controlling means for enabling from none to the plurality of levels of redundancy to operate on data being read or written from the arrayed disk drives.

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Boulder, CO, United States of America

David W Gordon