JPH0644011A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To considerably shorten the access time of a magnetic disk device by accessing to a non-volatile memory on data with much access rotation. CONSTITUTION:It is judged whether data on the physical address of a magnetic disk which is to be accessed from now exists in a data storage area in the non-volatile memory 3 or not by a flag string existing in the memory. When it exists in the data storage area, the data storage area concerned is searched, and a data write or read operation is executed as if the area is the magnetic disk 7. When it dose not exist in the data storage area, the magnetic disk 7 is accessed. When a data saving reservation flag in a statistic information is turned on, data on the data storage area is saving-operated at the time of reading the magnetic disk 7, and bit unit information concerned on the flag string existing in the memory is turned on.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device and, more particularly, to an access control system therefor.

[0002]

2. Description of the Related Art A conventional access control method in a magnetic disk device is to physically write or read data to or from a magnetic disk each time an access is made, or in the case of a read operation, immediately before that. When there is data at the physical address of the magnetic disk requested to be read in the contents read in the cache memory, the corresponding data read in the cache memory is sent to the requesting processing program. It is by means of returning it to the other party.

[0003]

In the conventional access control method in the magnetic disk device as described above, in order to transfer data at high speed, a magnetic disk having a short physical access time is used, or However, there is a drawback in that the program itself needs to be created so as to shorten the access time, taking into consideration the method of storing data in the magnetic disk device and the access timing to the magnetic disk. Further, there is a limit to the reduction of the physical access time of the magnetic disk, and there is a problem that the apparatus becomes expensive.

[0004]

A magnetic disk device according to the present invention comprises a battery-backed large-capacity non-volatile memory, and a data error detection unit for checking data errors in a predetermined area of the non-volatile memory. A controller is provided for statistically processing the number of accesses to a certain area of the magnetic disk and accessing the nonvolatile memory based on the statistical information, and a read-only memory for storing a program instructing the operation of the controller.

[0005]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a format diagram showing an example of contents of a nonvolatile memory of the embodiment of FIG. 1, and FIG. 3 is a data processing operation of the embodiment of FIG. 4 is a flowchart showing the hit rate calculation operation of the embodiment of FIG.

In FIG. 1, the magnetic disk device 10 of this embodiment receives a processing command from the host system 9 using this device via the interface section 1. The control unit (CPU) 8 reads a processing program corresponding to the command from the read-only memory (ROM) 2 and performs data processing according to the processing program.

When performing a data write or read operation on the magnetic disk 7, a data write or read process is performed on the magnetic disk 7 via the hardware control section 6. The non-volatile memory 3 is backed up by a battery 5, and the magnetic disk device 10
It retains its memory contents even when the power is turned off.
The non-volatile memory 3 stores information about the ax, the result of statistical processing of the information, the same data as the data recorded on the magnetic disk 7, and the management information indicating the position attribute. When accessing the data in the non-volatile memory 3, the data error detector 4 checks an error in the data including partial destruction of the content.

In FIG. 2, an in-memory presence flag string 11 shown in FIG. 2A is a physical fixed area of the magnetic disk 7,
For example, a sector or the like has bit unit information 11a corresponding to a bit unit, and since the data of the area of the magnetic disk 7 exists in this nonvolatile memory 3, the nonvolatile memory 3 is stored in the magnetic disk 7 It is information indicating that it can be targeted for processing instead of. The statistical information 12 shown in (b) is a table for calculating statistical information based on the number of times data is accessed, and stores information on how many times access has occurred in each physical fixed area of the magnetic disk 7. Access counter 12c, and a data save existence flag 12a and a data save reservation flag 12b to be processed on the non-volatile memory 3 in order to compare and judge the information with information on other areas. . The access index 13 shown in (c) is
Position information indicating where in the non-volatile memory 3 the corresponding data is stored is stored, and by the in-memory presence flag string 11, the data of the physical address of the magnetic disk 7 to be accessed from now on is stored in the non-volatile memory 3. When it is found that it exists in the inside, the access index 13 can be used to search for the head position of the corresponding data at high speed. The data storage area 14 shown in (d) corresponds to the physical information storage area of the magnetic disk 7, and processing can be performed as if the data were processed on the magnetic disk 7.

Next, the operation of the embodiment configured as described above will be described.

In the data processing operation, as shown in FIG. 3, first in step 21, the data of the physical address of the magnetic disk 7 to be accessed is present in the data storage area 14 in the non-volatile memory 3. Whether or not it is determined by the in-memory presence flag string 11. If it exists in the data storage area 14, step 26
Then, the corresponding data storage area 14 is searched, and the data writing or reading operation is performed as if the area is the magnetic disk 7. If it does not exist in the data storage area 14, the process proceeds to step 22 and the magnetic disk 7 is accessed. If the data save reservation flag 12b in the statistical information 12 is on (step 2
3) When the read operation is performed on the magnetic disk 7, a data save operation is performed on the data storage area 14 (step 24), and the corresponding bit unit information 11a of the in-memory presence flag string 11 is turned on (step 2).
5).

When the processing of step 26 or step 25 is completed, or when the data save reservation flag 12b is off in step 23, the process proceeds to step 27 and the access count of the access counter 12c of the statistical information 12 is updated. Next, in step 28, based on the contents processed in step 27, the area of the physical address with high access frequency is obtained by statistical processing, and step 29
At, it is determined whether or not the conditions for processing in the non-volatile memory 3 are met. If they match, the data save reservation flag 12b is turned on to set the use of the non-volatile memory 3 at the next access (step 30).

The hit rate calculation operation is a process which is activated when necessary, and performs the operation shown in FIG. That is, first, in step 31, the access hit rate of the data storage area 14 is calculated based on the statistical information 12. If the hit rate is declining overall (step 32),
Writing data to the magnetic disk 7 (step 33),
A process of turning off the data save existence flag 12a of the statistical information 12 (step 34) is performed, and a process of stopping the use of the corresponding part or all parts of the nonvolatile memory 3 is performed.

When the capacity of the non-volatile memory 3 is limited, the statistical information 12 is processed first and then the data storage area 14 is controlled to be used. Since the statistical information 12, the access index 13, and the data storage area 14 can be mapped in the same area, the non-volatile memory 3 can be effectively used.

[0015]

As described above, the magnetic disk device of the present invention is provided with a large-capacity non-volatile memory backed up by a battery, performs statistical processing of the number of accesses, and stores the statistical information in the non-volatile memory. By selecting and changing the data so that the frequently accessed data can be accessed to the non-volatile memory instead of the magnetic disk, the access time of the magnetic disk device can be significantly reduced. There is an effect that it becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a format diagram showing an example of contents of a nonvolatile memory of the embodiment of FIG.

FIG. 3 is a flowchart showing a data processing operation of the embodiment of FIG.

FIG. 4 is a flowchart showing a hit rate calculation operation of the embodiment of FIG.

[Explanation of symbols]

 1 interface unit 2 dedicated memory (ROM) 3 non-volatile memory 4 data error detection unit 5 battery 6 hardware control unit 7 magnetic disk 8 control unit (CPU) 9 host system 10 magnetic disk device 11 presence flag string in memory 11a bit unit Information 12 Statistical information 12a Data save existence flag 12b Data save reservation flag 12c Access counter 13 Access index 14 Storage area 21 to 34 steps

Claims (1)

[Claims] 1. A large-capacity non-volatile memory backed up by a battery, a data error detection unit for checking a data error for each constant area of the non-volatile memory, and statistical processing of the number of accesses to a certain area of a magnetic disk. A magnetic disk device comprising: a controller that accesses the non-volatile memory based on statistical information of the execution; and a read-only memory that stores a program that instructs the operation of the controller.