Write back method for RAID apparatus
First Claim
1. A write back method for making a RAID (i.e., redundant array of independent/inexpensive disk drives) apparatus carry out:
- an update information storing processing for storing update information of post-update data stored by a cache memory, which has been updated by update data sent from a host computer, in an update information management table;
a reference value generation processing, by obtaining the update information on the post-update data from the update information management table, for generating a first reference value expressing a load of a write processing by using a Small Write method, based on the aforementioned update information, and a second reference value expressing a load of a write processing by using a Read &
Bandwidth Write method;
a write method determination processing, by comparing the first reference value with the second reference value generated by the aforementioned reference value generation processing, for determining a write method out of either the Small Write method or the Read &
Bandwidth Write method, based on the comparison result; and
a write processing for reading the data stripe of the post-update data which is stored by the cache memory, and updating the data stripe by using a method determined by the write method determination processing.
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Accused Products
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.
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Citations
15 Claims
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1. A write back method for making a RAID (i.e., redundant array of independent/inexpensive disk drives) apparatus carry out:
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an update information storing processing for storing update information of post-update data stored by a cache memory, which has been updated by update data sent from a host computer, in an update information management table;
a reference value generation processing, by obtaining the update information on the post-update data from the update information management table, for generating a first reference value expressing a load of a write processing by using a Small Write method, based on the aforementioned update information, and a second reference value expressing a load of a write processing by using a Read &
Bandwidth Write method;
a write method determination processing, by comparing the first reference value with the second reference value generated by the aforementioned reference value generation processing, for determining a write method out of either the Small Write method or the Read &
Bandwidth Write method, based on the comparison result; and
a write processing for reading the data stripe of the post-update data which is stored by the cache memory, and updating the data stripe by using a method determined by the write method determination processing. - View Dependent Claims (2, 3, 4, 5)
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6. A RAID control apparatus, comprising:
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an update information storage unit for storing update information on post-update data stored by a cache memory, which has been updated by update data sent from a host computer, in an update information management table;
a reference value generation unit, by obtaining the update information on the post-update data from the update information management table, for generating a first reference value expressing a load of a write processing by using a Small Write method, based on the aforementioned update information, and a second reference value expressing a load of a write processing by using a Read &
Bandwidth Write method;
a write method determination unit, by comparing the first reference value with the second reference value generated by the reference value generation unit, for determining a write method out of either the Small Write method or the Read &
Bandwidth Write method, based on the comparison result; and
a write unit for reading the data stripe of the post-update data which is stored by the cache memory, and updating the data stripe by using a method determined by the write method determination unit. - View Dependent Claims (7, 8, 9, 10)
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11. A RAID apparatus equipping itself with a plurality of storage units for storing update data sent from a host computer, comprising:
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an update information storage unit for storing update information on post-update data stored by a cache memory, which has been updated by update data, in an update information management table;
a reference value generation unit, by obtaining the update information on the post-update data from the update information management table, for generating a first reference value expressing a load of a write processing by using a Small Write method, based on the aforementioned update information, and a second reference value expressing a load of a write processing by using a Read &
Bandwidth Write method;
a write method determination unit, by comparing the first reference value with the second reference value generated by the reference value generation unit, for determining a write method of either the Small Write method or the Read &
Bandwidth Write method, based on the comparison result; and
a write unit for reading the data stripe of the post-update data which is stored by the cache memory, and storing the data stripe by using a method determined by the write method determination unit in the plurality of storage units. - View Dependent Claims (12, 13, 14, 15)
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Specification