Disk array system and a method of avoiding failure of the disk array system
First Claim
1. A disk array system comprising:
- a channel adapter for controlling data transfer with respect to a host device;
a plurality of data disk drives configuring a RAID group,at least one spare disk drive provided as a spare for the data disk drives;
a disk adapter for controlling data transfer with respect to the data disk drives and the spare disk drive;
a cache memory used by the channel adapter and the disk adapter for storing data;
a control memory used by the channel adapter and the disk adapter for storing control information;
a backup storage provided separately from the data disk drives and the spare disk drive;
a first control unit provided in the disk adapter for observing occurrence of access error with respect to the data disk drives, the first control unit, when the frequency of occurrence of the access error exceeds a predetermined threshold, copying data stored in the data disk drive exceeding the threshold to the spare disk drive via the cache memory;
a second control unit provided in the disk adapter for processing access request directed to the RAID group during the copying process, the second control unit making the backup storage take over a write request directed to the RAID group; and
a third control unit provided in the disk adapter for copying data written in the backup storage by the second control unit to the data disk drives and the spare disk drive other than the data disk drive exceeding the threshold when the copying process by the fist control unit is finished.
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Accused Products
Abstract
The invention is intended to reduce disk access during data transfer from a disk in which occurrence of failure is anticipated to a spare disk as much as possible so that occurrence of double-failure is prevented in advance. When occurrence of failure in a disk which configures a RAID group, contents stored in the disk is copied to the spared disk. Simultaneously, another RAID group is paired with the above described RAID group and a secondary volume is provided therein. A write request is directed to the secondary volume. A differential bitmap controls a update data. Data which is not updated is read out from the primary volume, and data which is already updated is read from the secondary volume. When data transfer is completed, contents stored in the secondary volume are copied to the primary volume.
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Citations
20 Claims
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1. A disk array system comprising:
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a channel adapter for controlling data transfer with respect to a host device; a plurality of data disk drives configuring a RAID group, at least one spare disk drive provided as a spare for the data disk drives; a disk adapter for controlling data transfer with respect to the data disk drives and the spare disk drive; a cache memory used by the channel adapter and the disk adapter for storing data; a control memory used by the channel adapter and the disk adapter for storing control information; a backup storage provided separately from the data disk drives and the spare disk drive; a first control unit provided in the disk adapter for observing occurrence of access error with respect to the data disk drives, the first control unit, when the frequency of occurrence of the access error exceeds a predetermined threshold, copying data stored in the data disk drive exceeding the threshold to the spare disk drive via the cache memory; a second control unit provided in the disk adapter for processing access request directed to the RAID group during the copying process, the second control unit making the backup storage take over a write request directed to the RAID group; and a third control unit provided in the disk adapter for copying data written in the backup storage by the second control unit to the data disk drives and the spare disk drive other than the data disk drive exceeding the threshold when the copying process by the fist control unit is finished. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of avoiding failure of a disk array system comprising a channel adapter for controlling data transfer with respect to a host device, a plurality of data disk drives configuring a RAID group, at least one spare disk drive provided as a spare for the data disk drives, a disk adapter for controlling data transfer with respect to the data disk drives and the spare disk drives, a cache memory used by the channel adapter and the disk adapter for storing data, a control memory used by the channel adapter and the disk adapter for storing control information, a backup storage provided separately from the data disk drives and the spare disk drive comprising:
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a first step of observing occurrence of an access error with respect to the data disk drives and judging whether or not the frequency of occurrence of the access error exceeds a predetermine threshold; a second step of copying data stored in the data disk drive exceeding the threshold to the spare disk drive when the data disk drive exceeding the threshold is detected in the first step; a third step of associating the RAID group with the backup storage by starting the copying process in the first step; a fourth step of judging whether or not an access request directed to the RAID group has issued during the copying process in the first step; and a fifth step of writing data in the backup storage associated in the third step when issue of the access request is detected in the fourth step, and if the access request is a write request. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method of using a disk drive in a disk array system comprising a plurality of disk drives configuring the RAID group, comprising:
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a faulty drive detecting step for observing occurrence of an access error with respect to the each disk drive configuring the RAID group, and when the frequency of the access error exceeds a predetermined threshold, determining that it is a faulty disk drive; a data copying step for copying data stored in the faulty disk drive to a normal disk drive other than the each disk drive configuring the RAID group when the faulty disk drive is detected in the fault disk drive detecting step, an access request detecting step for detecting whether or not an access request directed to the RAID group has issued during the copying process in the data copying step; and an access processing step for writing data relating to the write request to a normal disk drive different from the normal disk drive in which the data is copied when a write request is detected in the access request detecting step. - View Dependent Claims (18, 19, 20)
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Specification