Disc device
AssigneeNEC Corporation
InventorSHUN KURITA
Life of this patent
Estimating the term…
Abstract
In a disc device according to the present invention, when a controller 2 abandons a block from a cache memory 4 used as a primary cache, it is determined whether or not the number of readings of data in the block exceeds the specified number of times. Only when the number of readings exceeds the specified number of times, the block is written into an SSD 8 used as a secondary cache. When the number of readings is equal to or smaller than the specified number of times, the block is rewritten into an HDD 7.
Claims8
A disc device comprising:
- a disc;
- a primary cache that records a copy of a part of data recorded in the disc therein;
- a secondary cache formed of an SSD, the secondary cache recording a copy of a part of data recorded in the disc therein;
- and
- a control unit, wherein
- in the case where the number of readings of a block selected to be abandoned in the primary cache in order to make a blank area in the primary cache exceeds a threshold, the control unit records the block in the secondary cache, and
- at read request,
- when data to be read exists in the primary cache, the control unit returns the data to be read in the primary cache to a requester,
- and when the data to be read does not exist in the primary cache and exists in the secondary cache, the control unit writes a block containing the data to be read that exists in the secondary cache into the primary cache and then, returns the data to be read to the requester.
A secondary cache utilizing method in a disc device including a disc, a primary cache that records a copy of a part of data recorded in the disc therein and a secondary cache formed of an SSD, the secondary cache recording a copy of a part of data recorded in the disc therein, wherein
- a control unit,
- in the case where the number of readings of a block selected to be abandoned in the primary cache in order to make a blank area in the primary cache exceeds a threshold, the control unit records the block in the secondary cache, and
- at read request,
- when data to be read exists in the primary cache, the control unit returns the data to be read in the primary cache to a requester, and
- when the data to be read does not exist in the primary cache and exists in the secondary cache, the control unit writes a block containing the data to be read that exists in the secondary cache into the primary cache and then, returns the data to be read to the requester.
A computer-readable recording medium having a program for allowing a CPU mounted in a disc device including a disc, a primary cache that records a copy of a part of data recorded in the disc therein and a secondary cache formed of an SSD, the secondary cache recording a copy of a part of data recorded in the disc therein to function as a control unit, wherein
- in the case where the number of readings of a block selected to be abandoned in the primary cache in order to make a blank area in the primary cache exceeds a threshold, the control unit records the block in the secondary cache, and
- at read request,
- when data to be read exists in the primary cache, the control unit returns the data to be read in the primary cache to a requester, and
- when the data to be read does not exist in the primary cache and exists in the secondary cache, the control unit writes a block containing the data to be read that exists in the secondary cache into the primary cache and then, returns the data to be read to the requester.
Dependencies are inferred from the claim text.