JPH11306664A - External storage device - Google Patents

Abstract

(57) [Summary] In a conventional external storage device with a cache memory and a write data memory, a storage medium is accessed at independent timings when a cache memory mishits and when a write data memory overflows. The number of accesses to the storage device increases, and the efficiency of reducing power consumption does not increase. An external storage device according to the present invention includes a power save controller between a cache controller and a write data memory controller. By performing data transfer from the write data memory to the storage medium when performing access to the storage medium that occurs when a cache mishit occurs, the number of accesses to the storage medium that occurs when the write data memory overflows can be reduced. The number of times of starting the spindle motor can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external storage device having a cache memory and a write data memory, and using a magnetic disk, an optical disk or the like as a storage medium.

[0002]

2. Description of the Related Art In notebook computers and portable information terminals,
Generally, a battery is used as a driving power supply.
Therefore, the time during which the user can carry and use these devices is limited by the battery drive time. Prolonging the battery drive time is a great selling point of the mobile terminal, and various companies have devised to prolong the battery operation time. As an example, there is a method of reducing power consumption by stopping a spindle motor of a hard disk that consumes a large amount of power when there is no access to the hard disk for a certain period of time. However, in this method, depending on the relationship between the set time and the disk access timing, the disk device may frequently start and stop the spindle motor that consumes the most power, and the effect of reducing power consumption may be reduced. There was a problem that it was not enough. Therefore, as disclosed in Japanese Patent Laid-Open No. 5-101514, an external storage device having a cache memory and a write data memory in a hard disk is disclosed. An example of the present external storage device will be described with reference to FIG.

First, in FIG. 7, 1 is a host device (host) such as a CPU (Central Processing Unit), 2 is a bus I / F (interface) circuit,
3 is a controller, 4 is a cache controller, 5 is a cache memory, 6 is a read circuit, 7 is a write data memory controller, 8 is a write data memory, 9 is a write circuit, 10 is a power save controller 1, and 11 is a disk storage. Medium, 12 is a power supply circuit, 13
Is a spindle motor, and 14 is an external storage device. FIG.
As shown in FIG. 5, by providing the cache memory 5 and the write data memory 8 between the storage medium 11 and the bus I / F circuit 2, when the host accesses the external storage device 14, the cache memory 5 and the write data The data memory 8 can be accessed. In this case, turning off the spindle motor of the disk other than when accessing data to the disk when the cache mishits or when the write data memory 8 overflows reduces the frequency of access to the disk and has the effect of suppressing power consumption. can get.

[0004]

However, in the above conventional example, the access timing to the storage medium at the time of a memory mishit in the cache memory and the access timing to the storage medium at the time of overflow of the write data memory in the write data memory. Is not related between
Since the storage media are accessed at independent timings, there is a problem that the number of accesses to the external storage device increases and the efficiency of reducing power consumption does not increase.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. By reducing the number of accesses from a cache memory and a write data memory to a storage medium, the number of starts of a spindle motor of the storage medium is reduced. The purpose is to achieve lower power consumption.

[0006]

An external storage device according to the present invention includes a storage medium for storing data, a cache memory for caching data in the storage medium, and write data for writing data to be written to the storage medium. Monitoring a memory, a cache controller controlling the cache memory, a write data memory controller controlling the write data memory, a controller controlling the storage medium, and a controller controlling the storage medium,
At least controlling the power of the storage medium, monitoring the cache memory controller, and writing the data from the write data memory to the storage medium at the time of accessing the storage medium when a cache mishit occurs. A power save controller for controlling the memory controller is provided.

The external storage device according to the present invention is characterized in that at least one of the cache memory and the write data memory is constituted by a large-capacity nonvolatile memory.

An external storage device according to the present invention is characterized in that at least one of a cache memory and a write data memory has a mechanism capable of being added or replaced.

An external storage device according to the present invention includes a data compression circuit provided at least on one input side of a cache memory and a write data memory, and an output of the cache memory and the write data memory provided with the data compression circuit. A data expansion circuit is provided on the side.

In the external storage device according to the present invention, when the write data memory controller writes data to be written to the storage medium to the write data memory, if the storage medium is operating, the write memory data does not overflow. In both embodiments, data is written from the write data memory to the storage medium.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 In FIG. 1, 1
Is a host such as a CPU, 2 is a bus I / F circuit, 3 is a controller, 4 is a cache controller, 5 is a cache memory, 6 is a read circuit, 7 is a write data memory controller, 8 is a write data memory, and 9 is a write. Circuit, 10 is a power save controller 1, 11 is a storage medium, 12 is a power supply circuit, 13 is a spindle motor,
4 is an external storage device, 15 is the cache controller 4
And a power save controller 2 that monitors the operation status of the spindle motor 13 for driving the storage medium and controls the write data memory controller. (1) Power On → Power Save Mode → Normal Mode First, transition from the power on of the external storage device 14 to the power save mode and transition to the normal mode will be described with reference to FIG. When the power of the external storage device 14 is turned on (step 20), the spindle motor 13 inside the storage medium 11 starts (step 21). There is no access to the external storage device 14 for a certain period of time (step 2
4), if the spindle motor off time has elapsed (YES in step 25), the power save controller 1 (10) stops the spindle motor 13 (step 26) and resets a part of the circuit of the power save controller 10. The apparatus enters a power save mode in which all power supplies are cut off (step 27). Thereafter, when the host 1 accesses the external storage device (YE in step 28).
S), the power save controller 10 shifts to the normal mode and turns on the power supplies other than the spindle motor 13 (step 29).

(2) Data Write Next, a case where the request in step 24 or 28 is a data write from the host 1 to the external storage device 14 will be described. When there is a data write request from the host 1 (write in step 30), the host 1 writes data to the write data memory 8 (step 31). As a result, when the write data memory 8 overflows (Y in step 32).
ES), if the spindle motor 13 is off (off in step 33), the power save controller 1 (1
0) turns on the spindle motor 13 (step 3).
5), the write data memory 8 writes all data to a predetermined address of the storage medium (step 34). In the present invention, when the write data memory 8 does not overflow (NO in step 32), the spindle motor 13
Is turned on (step 36 is on), all the data in the write data memory 8 is written to a predetermined address of the storage medium using this motor operation (step 3).
4) It is characterized by the following. By this operation, the number of times of overflow can be reduced.

(3) Data Read Next, the case where the request in step 24 or 28 is a data read from the host 1 to the external storage device 14 will be described. If there is a data read request from the host 1 (read in step 30) and the data exists in the cache memory 5 (hit in step 37), the data is transferred from the cache memory 5 to the host without accessing the storage medium 11. . On the other hand, if the data does not exist in the cache memory 5 (a miss in step 37), the spindle motor 13
Is off (Step 38 is off), the spindle motor 13 is turned on (Step 43), and data is transferred from the storage medium 11 to the host 1 (Step 39). Also,
Data is written from the storage medium 11 to the cache memory 5 (step 40). The present invention is characterized in that all the data in the write data memory 8 is written to a predetermined address of the storage medium 11 by utilizing this motor operation (step 41).

Next, the effects of the present invention will be described with reference to FIGS. FIG. 3 is a conceptual diagram in which the present invention is simplified. For the sake of simplicity, it is assumed here that the cache memory has five sectors, and a cache miss occurs once every five times (the fifth time). Also,
It is assumed that the write data memory has five sectors and the write data memory overflows at a rate of one out of five times (fifth time). If there is no access for a fixed time (3 clocks), the spindle motor is turned off.

FIG. 4 shows the driving frequency of the spindle motor when data writing and reading are alternately performed on the conventional external storage device under these conditions. In this case, the timing of writing data to the storage medium at the time of write overflow and the timing of reading data to the storage medium at the time of a cache mishit are not related, so that the number of spindle motor accesses is seven. On the other hand, in the external storage device of the present invention, by writing to the storage medium of the write data memory using the time of reading the storage medium at the time of cache mishit, as shown in FIG. Under the same conditions, the number of spindle motor accesses can be reduced from seven to four. In other words, under these conditions,
The present invention can reduce the number of motor starts by about 40% compared to the conventional example. As described above, according to the present invention, the number of times of starting the spindle motor can be reduced, so that lower power consumption can be achieved.

As described above, this embodiment includes: A storage medium for storing data; A bus I / F circuit that interfaces data with the host; A cache memory for caching data in the storage medium between a host and the storage medium; A write data memory for writing data in the storage medium between the host and the storage medium; A cache controller for controlling the cache memory; A write data memory controller for controlling the write data memory; A power save controller 1 for controlling the power of the entire apparatus; A controller for controlling the storage medium; In an external storage device composed of the power save controller 2 for monitoring the operation status of the cache memory controller and the spindle motor for driving the storage medium and controlling the write data memory controller, the storage medium generated when a cache mishit occurs. At the time of access,
By writing data from the write data memory to the storage medium, the number of accesses to the storage medium that occurs when the write data memory overflows is reduced, the number of times the spindle motor of the storage medium is started is reduced, and power consumption is reduced. It is characterized by the following. Although the power save controllers 1 and 2 have been described separately, one power save controller may be used.

Further, the cache memory and the data write memory are constituted by nonvolatile memories. By doing so, the power can be turned off while retaining the data, so that the power consumption can be further reduced.

Further, the cache memory and the data write memory can be added. For this reason, the amount of data written to these memories can be increased. This allows
The number of accesses to the storage medium can be further reduced,
It is possible to reduce the number of times the spindle motor is started, thereby achieving lower power consumption.

Embodiment 2 Next, an embodiment of the present invention is shown in FIG. Here, 17 is a data compression circuit 1 for compressing data in the storage medium 11, 16 is a data expansion circuit for expanding data in the cache memory, and 18 is a data expansion circuit for returning to the original data. The data compression circuits 2 and 19 for compression are data expansion circuits 2 for restoring the data in the write data memory. By providing a data compression circuit and a data decompression circuit, the amount of data written to these memories can be increased. This makes it possible to further reduce the number of accesses to the storage medium, reduce the number of times the spindle motor is started, and achieve lower power consumption.

[0020]

The present external storage device is provided between the cache controller 4 and the write data memory controller 7.
A power save controller 2 (15) is provided, which performs data transfer from the write data memory to the storage medium when performing access to the storage medium that occurs at the time of a cache mishit. And the number of times the spindle motor of the storage medium is started can be reduced. As described above, the number of times of starting the spindle motor of the storage medium can be reduced, and power consumption can be reduced. Further, by reducing the number of times the spindle motor is started, an effect of extending the life of the apparatus can be expected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an external storage device of the present invention.

FIG. 2 is a flowchart of an embodiment of the present invention.

FIG. 3 is a conceptual diagram showing access between a cache memory, a write data memory, and a storage medium device.

FIG. 4 is a motor drive frequency diagram when an external storage device is accessed in a conventional example.

FIG. 5 is a diagram showing a motor driving frequency when an external storage device is accessed in the present invention.

FIG. 6 is another configuration diagram of the present invention.

FIG. 7 is a configuration diagram of a conventional external storage device.

[Explanation of symbols]

1 host, 2 bus I / F circuit, 3 controller,
4 cache controller, 5 cache memory,
6 read circuit, 7 write data memory controller, 8 write data memory, 9 write circuit, 10
Power save controller 1, 11 Storage medium, 12
Power supply circuit, 13 spindle motor, 14 external storage device, 15 power save controller 2, 16 data decompression circuit 1, 17 data compression circuit 1, 18 data compression circuit 2, 19 data decompression circuit 2.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 19/00 501 G11B 19/00 501B

Claims (5)

[Claims] A storage medium that stores data; a cache memory that caches data in the storage medium; a write data memory that writes data to be written to the storage medium; a cache controller that controls the cache memory; A write data memory controller that controls the write data memory; a controller that controls the storage medium; and a controller that controls the storage medium, and at least controls the power of the storage medium and controls the cache memory controller. Monitoring and writing data from the write data memory to the storage medium at the time of access to the storage medium which occurs at the time of cache mishit,
An external storage device comprising a power save controller for controlling the write data memory controller. 2. The external storage device according to claim 1, wherein at least one of the cache memory and the write data memory is constituted by a large-capacity nonvolatile memory. 3. The external storage device according to claim 1, wherein at least one of the cache memory and the write data memory has a mechanism that can be added or replaced. 4. A data compression circuit is provided on at least one input side of the cache memory and the write data memory, and a data expansion circuit is provided on an output side of the cache memory and the write data memory provided with the data compression circuit. 2. The external storage device according to claim 1, wherein: 5. When writing data to be written to the storage medium into the write data memory, the write data memory controller may transfer the write data from the write data memory to the storage medium without overflow if the storage medium is in operation. 2. The external storage device according to claim 1, wherein data is written to the external storage device.