JP2753391B2 - Disk device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a disk device having a cache memory.

[Prior art] Conventionally, as described in the Alps Electric hard disk DRPO40C product specification, to reduce the power consumption of a magnetic disk device, as described in this known example, a command to put the magnetic disk into a low power consumption state is issued. , The host computer went into effect. Alternatively, when no command is issued to the magnetic disk for a certain period, the magnetic disk itself has automatically shifted to the low power consumption state.

[Problems to be Solved by the Invention] The above-mentioned prior art does not consider the power consumption of a magnetic disk having a disk cache and does not contribute to reducing the power consumption of the magnetic disk. In the case of a magnetic disk with a disk cache, even if a host computer requests access to the disk,
The data exists in the cache memory (hit)
Sometimes, there is no need to access the disk, and the disk power consumed during that time is useless. Therefore,
Even if there is an access request from the host, if the requested data is hit, it is desirable that the disk has shifted to a low power consumption state.

However, since the host computer does not know whether the requested data has been hit or missed, the host computer cannot put the disk into a low power consumption state while the requested data is hit, resulting in a wasteful operation. Power was consumed.

An object of the present invention is to reduce the power consumption of a magnetic disk device having a disk cache.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for removing a magnetic disk only when data requested from a host does not exist in a cache memory (miss hit) and the magnetic disk is accessed. At other times, the magnetic disk was put into a low power consumption state. That is, the transition of the operation state of the magnetic disk is performed by the controller of the magnetic disk regardless of the host computer.

The low power consumption state of the magnetic disk is defined as ENDEC or R
The power to the signal processing circuit such as the / W circuit is turned off, and the spindle motor of the disk is stopped, or the power to the signal processing circuit is turned off, but the spindle motor is operating. Say.

[Operation] Since the controller of the magnetic disk manages the cache memory, it is possible to determine whether the data requested by the host has hit or missed. If the controller of the magnetic disk switches between the operation state of the magnetic disk and the low power consumption state, the magnetic disk can be set to the low power consumption state while data is hit.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram of hardware according to one embodiment of the present invention.

In FIG. 2, reference numeral 201 denotes a host computer, 202 denotes a host interface controller, 203 denotes a disk / cache memory controller, and 204 denotes a cache memory.

205 encoder-duder data separators and 206
The R / W circuit 207 and the R / W circuit 207 are signal processing circuits. The power save control 2 allows the disk / cache memory controller 203 to control ON / OFF of the power supply.

201 is a spindle motor driver, and the disk / cache memory controller 203 can control ON / OFF of the spindle motor 211 via the spindle motor driver 210 by the power save control 1.

The processing of the present invention will be described with reference to FIG. Steps
The process starts at 11. In step 12, the disk cache memory controller 203 turns off the spindle motor 211 using the power save control 2. At the same time, the power of the signal processing circuit is turned off using the power save control 1.

Next, in step 13, the disk cache memory controller 203 waits in a low power consumption state until a request comes from the host. This low power consumption state is, for example,
Stopping the clock input to the disk cache memory controller to save power.

When a request is received from the host, the disk
The cache memory controller 203 releases the low power consumption state.

Next, in step 15, the disk cache memory controller 203 determines whether the data requested by the host has hit or missed. If there is a hit, data transfer between the cache memory and the host is performed in step 16. If there is a miss in step 15, in step 17, the spindle motor 21
Turn on 1 and also turn on the power of the signal processing circuit in the magnetic disk. In step 18, data is transferred between the magnetic disk and the host via the cache memory 204. In step 19, the spindle motor 211 of the magnetic disk is turned off again, and the power of the signal processing circuit in the magnetic disk is turned off. To OFF.

 Another embodiment will be described with reference to FIG.

In this embodiment, while the hit rate is low, the spindle motor
ON and OFF are not performed frequently.

Steps 301 to 309 are the steps shown in FIG.
This is the same as 11 to step 19. In this embodiment, when the request from the host misses in step 305, the disk cache memory controller 203 proceeds to step 310.
It is determined whether the hit rate up to the present is high or low. The value used as a criterion of high or low may be determined separately, and this numerical value may be compared with the current hit rate.

When the hit rate is high, the same processing as in the above-described embodiment is performed. If the hit rate is low, then if the spindle motor 211 of the disk is off at step 311, it is turned on. Next, in step 312, data is transferred between the disk and the host via the cache memory 204.

[Effect of the Invention] According to the present invention, the spindle motor of the magnetic disk is operated only at the time of a mishit, so that power consumption is reduced and power consumption can be reduced.

Also, while the hit rate is low, the spindle motor can always be operated,
Time delay due to ON / OFF can be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart showing the processing of one embodiment of the present invention, FIG. 2 is a block diagram of the hardware of FIG. 1, and FIG. 3 is a flowchart showing the processing of another embodiment of the present invention. EXPLANATION OF SYMBOLS 203: Disk / cache memory controller, 204
…… Cache memory, 205 …… Encoder / decoder data separator, 206 …… Wave shaper, 207 …… R / W
IC, 211 ... Spindle motor.

Continued on the front page (72) Inventor Yuji Shimada 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi Micro Software Systems Co., Ltd. In Micro Software Systems (72) Inventor Yoshito Suzuki 5-20-1, Kamimizuhoncho, Kodaira-shi, Tokyo Inside Semiconductor Design & Development Center, Hitachi, Ltd. (56) References JP-A-2-214060 (JP, A)

Claims (2)

(57) [Claims] 1. A disk device having a magnetic disk, a cache memory, and a controller for controlling the magnetic disk and the cache memory, wherein the controller receives the data request from a host computer in response to the request in the cache memory. The presence / absence of data is determined.If the requested data is present in the cache memory, the controller issues a signal to stop the spindle motor of the magnetic disk.If the requested data is not present, the controller issues a signal. A disk drive, comprising: a controller for issuing a signal for operating a spindle motor of the magnetic disk. 2. The disk drive according to claim 1, wherein when the hit ratio of the data requested by the host computer does not satisfy a predetermined criterion, the operation of the spindle motor of the magnetic disk is switched by the control means. A disk device characterized by the absence.