Abstract: A response of a disk device during rebuild can be sped up. A disk array control device determines whether or not there is a normal read request during rebuild. If there is a read request during rebuild, data is read by sequentially switching a plurality of disk devices in a certain block size unit lower than a block size in which each disk device reads data during normal read.

Abstract: In a system for dispersively storing data and parity in a plurality of storage devices, information in a first storage device is restored by using information stored in the storage devices other than the first storage device when the first storage device fails. And information in a non-restored area in the first storage device and information in a second storage device are restored by using information stored in the storage devices other than the first and the second storage devices when the second storage device fails while the information in the first storage device is being restored.

Abstract: A RAID apparatus that at least duplicates identical data to store thus duplicated data, which, when an instruction of writing data is given, writes data to a local cache and to a mirror cache, and writes data of the local cache to a primary disk and writes data of the mirror cache to a secondary disk. When an instruction of reading out data is given, and specified data is retained in the caches, the RAID apparatus outputs valid data of the local cache or the mirror cache, while when specified data is not retained in the caches, the RAID apparatus outputs valid data of the primary disk or the secondary disk.

Abstract: A method and apparatus for enhancing performance of parity check in computer readable media is provided. For example, in a RAID (N+1) configuration, a virtual data strip is added for a calculation of parity. Data of the virtual data strip is set so that a predetermined portion of a data area in the virtual data strip has a predetermined value. Consequently, performance of parity check performed in a data processing system having a RAID configuration can be enhanced.

Abstract: In case an error statistics of one of the disk drives exceeds a predetermined threshold, the disk is determined as a suspect disk drive. A recovery mode is set successively. During the time when a setting of the recovery mode is in progress and no access is made from a host 16 in this time, the address range of the suspect disk drive is specified. At the same time, a processing is started in that the data of the suspect disk is copied to a spare disk 34 sequentially to recover the data. The data of the suspect disk drive is copied to the spare disk drive 34 to recover the data when the address range of the suspect disk drive does not correspond to the write failure address range of a management table 48. The data of a normal disk drive is copied to the spare disk drive 34 to recover the data when the address range of the suspect disk drive corresponds to the write failure address range of the management table 48.

Abstract: In the present invention, for each set of blocks [#(0) to #(N?1)] storing update data, a history block [#(N)] storing an update state value, for example, a generation, time or check code, showing an update state is provided, constituting a set of management data as a check object. When writing update data on a disk, a new update state value is calculated for the same set of management data and stored in memory as update state confirmation value. The new update state value is also set as write data in the history block in the same set of management data, and the entire of the set of management data including update data and update state value are written onto a disk. The history block is read and disk write omissions are detected by comparing the update state value and the update state confirmation value stored in memory.

Abstract: Storage destination controller devices wherein N number of data strips and M number of parity strips comprised in each stripe are determined so that the parity strips are not continuously stored to the same memory device between two consecutive stripes when a plurality of stripes, each comprising the N number of data strips and the M number of parity strips of different types, are distributed and stored to the N+M number of memory devices.

Abstract: To provide a staging method capable of detecting an error in data read from a disk device during staging, a disk array control apparatus 100 includes a data read unit 101 for reading data, a first reference data generation unit 102 for generating first reference data from the read data, a second reference data generation unit 103 for similarly generating second reference data, a true-false determination unit 104 for determining whether or not the data read by the data read unit 101 is correct, and a data write unit 105 for writing data to cache memory.

Abstract: When a write-back request for writing back new data in a cache memory to disk devices forming a redundant configuration of RAID is generated, a write-back processing unit, reserves a parity buffer area in the cache memory, generates new parity, and then, writes the new data and the new parity to the corresponding disk devices. When an error in which the consistency of RAID is broken occurs in a plurality of the disk devices upon write performed by the write-back processing unit, a recovery processing unit reserves, in the cache memory, a cache stripe area storing data of the entire stripe including the new data which is to be written back, and causes the cache control unit to manage it.

Abstract: A RAID control apparatus comprises at least a cache memory; an update information management table for storing update information; an update information storage unit for storing, in the update information management table, update information by detecting a data update; a reference value generation unit for generating a reference value expressing a load of a write back processing by using a Small Write method and a Read & Bandwidth Write method based on the update information; a write method determination unit for determining a write method according to the reference value and a write unit for carrying out a write processing, in order to provide a write back method for a RAID apparatus capable of improving a processing speed at the time of updating even in the case of including the processing of updating a part of data stripes.

Abstract: A response of a disk device during rebuild can be sped up. A disk array control device determines whether or not there is a normal read request during rebuild. If there is a read request during rebuild, data is read by sequentially switching a plurality of disk devices in a certain block size unit lower than a block size in which each disk device reads data during normal read.

Abstract: A method and apparatus for enhancing performance of parity check in computer readable media is provided. For example, in a RAID (N+1) configuration, a virtual data strip is added for a calculation of parity. Data of the virtual data strip is set so that a predetermined portion of a data area in the virtual data strip has a predetermined value. Consequently, performance of parity check performed in a data processing system having a RAID configuration can be enhanced.

Abstract: A RAID control apparatus comprises at least a cache memory; an update information management table for storing update information; an update information storage unit for storing, in the update information management table, update information by detecting a data update; a reference value generation unit for generating a reference value expressing a load of a write back processing by using a Small Write method and a Read & Bandwidth Write method based on the update information; a write method determination unit for determining a write method according to the reference value and a write unit for carrying out a write processing, in order to provide a write back method for a RAID apparatus capable of improving a processing speed at the time of updating even in the case of including the processing of updating a part of data stripes.

Abstract: In a system for dispersively storing data and parity in a plurality of storage devices, information in a first storage device is restored by using information stored in the storage devices other than the first storage device when the first storage device fails. And information in a non-restored area in the first storage device and information in a second storage device are restored by using information stored in the storage devices other than the first and the second storage devices when the second storage device fails while the information in the first storage device is being restored.

Abstract: When a write-back request for writing back new data in a cache memory to disk devices forming a redundant configuration of RAID is generated, a write-back processing unit, reserves a parity buffer area in the cache memory, generates new parity, and then, writes the new data and the new parity to the corresponding disk devices. When an error in which the consistency of RAID is broken occurs in a plurality of the disk devices upon write performed by the write-back processing unit, a recovery processing unit reserves, in the cache memory, a cache stripe area storing data of the entire stripe including the new data which is to be written back, and causes the cache control unit to manage it.

Abstract: In the present invention, for each set of blocks [#(0) to #(N-1)] storing update data, a history block [#(N)] storing an update state value, for example, a generation, time or check code, showing an update state is provided, constituting a set of management data as a check object. When writing update data on a disk, a new update state value is calculated for the same set of management data and stored in memory as update state confirmation value. The new update state value is also set as write data in the history block in the same set of management data, and the entire of the set of management data including update data and update state value are written onto a disk. The history block is read and disk write omissions are detected by comparing the update state value and the update state confirmation value stored in memory.

Abstract: In the present invention, for each set of blocks [#(0) to #(N?1)] storing update data, a history block [#(N)] storing an update state value, for example, a generation, time or check code, showing an update state is provided, constituting a set of management data as a check object. When writing update data on a disk, a new update state value is calculated for the same set of management data and stored in memory as update state confirmation value. The new update state value is also set as write data in the history block in the same set of management data, and the entire of the set of management data including update data and update state value are written onto a disk. The history block is read and disk write omissions are detected by comparing the update state value and the update state confirmation value stored in memory.

Abstract: Storage destination controller devices wherein N number of data strips and M number of parity strips comprised in each stripe are determined so that the parity strips are not continuously stored to the same memory device between two consecutive stripes when a plurality of stripes, each comprising the N number of data strips and the M number of parity strips of different types, are distributed and stored to the N+M number of memory devices.

Abstract: In case an error statistics of one of the disk drives exceeds a predetermined threshold, the disk is determined as a suspect disk drive. A recovery mode is set successively. During the time when a setting of the recovery mode is in progress and no access is made from a host 16 in this time, the address range of the suspect disk drive is specified. At the same time, a processing is started in that the data of the suspect disk is copied to a spare disk 34 sequentially to recover the data. The data of the suspect disk drive is copied to the spare disk drive 34 to recover the data when the address range of the suspect disk drive does not correspond to the write failure address range of a management table 48. The data of a normal disk drive is copied to the spare disk drive 34 to recover the data when the address range of the suspect disk drive corresponds to the write failure address range of the management table 48.

Abstract: A RAID apparatus that at least duplicates identical data to store thus duplicated data, which, when an instruction of writing data is given, writes data to a local cache and to a mirror cache, and writes data of the local cache to a primary disk and writes data of the mirror cache to a secondary disk. When an instruction of reading out data is given, and specified data is retained in the caches, the RAID apparatus outputs valid data of the local cache or the mirror cache, while when specified data is not retained in the caches, the RAID apparatus outputs valid data of the primary disk or the secondary disk.