JPS6222162A - Disk cash control system - Google Patents

Abstract

PURPOSE:To enable a rapid readout and to prevent the loss of data even in power failure by storing data management information at both a cash memory and a disk device. CONSTITUTION:In a start-up time, all of the data management information stored at an i-list area within a disk device 1 is stored at a cash memory 2. And when the readout of the data management information is requested by a system unit (CPU main memory) 4, the data management information within the memory 2 is read out and transferred to the unit 4. Also, when the write of the data management information is requested from the unit 4, the data management information is written on both the i-list area in the disk unit and the memory 2. Thereby, the rapid readout of the data management information can be realized. Also, the data management information is not lost even in the power failure of a power source.

Description

Detailed Description of the Invention [Summary] In a disk cache control method in which data management information in a file system is stored in a cache memory and accessed, a disk device that stores data and data management information, and at least the data management information are stored. and a disk controller for accessing the disk device and cache memory.

Stores data management information in cache memory at startup,
And when there is a request to read data management information, is there a system to transfer the data management information read from the cache memory? When there is a request to write data management information or data management information, the data management information is controlled to be written to the disk device and cache memory, respectively.

[Industrial application field]

The present invention relates to a disk cache control method that controls data management information in a file system to be held in a cache memory and accessed.

[Conventional technology]

Conventional 1 For example, when building a UNIX-type file system and writing data to or reading data from a disk device that makes up the system, data management information for managing this data is read from the disk device each time. The information was managed accordingly.

In addition, in order to quickly read data management information from a disk device and execute predetermined access processing, an area corresponding to the area (address area) of the disk device that stores the data management information is stored in a semiconductor memory (RAM, etc.). After turning on the power, access the data management information for the area, and then turn off the power switch.
In the case of F, there is also a method of configuring a so-called RAM disk device in which data management information stored in the RAM is stored in a predetermined area of the corresponding disk device.

[Problem that the invention seeks to solve]

If data management information was accessed from a disk device each time a file system was constructed and data was accessed, the so-called "i-list area", which is an area where all the data management information is stored, would be frequently accessed. There is a problem in that it becomes difficult to quickly access data when the need arises.

In addition, if a so-called RAM disk is placed in an area corresponding to the ``i-list area'' stored in the disk device, data management information in the ``i-list area'' stored in the RAM disk can be quickly accessed. This makes it possible to access desired data. However, if there is a power outage for some reason, for example, the data management information stored in the ``i-me list area'' will be lost, resulting in a problem of lack of reliability.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a cache memory and adopts a configuration in which all data management information stored in the "i-list area" in the disk device is stored in the cache memory at the time of startup, And when there is a request to read data management information from the host, it controls to read the data management information stored in the cache memory and transfer it to the host, and when there is a request from the host to write data management information In addition, the data management information is controlled to be written to both the disk device and the cache memory.

Means for solving the problems will be explained using the configuration of one embodiment of the present invention shown in FIG.

In FIG. 1, 1 is a disk device, and 1-1 is an i-list file area that collectively stores data management information.

1-2 represents a data area for storing data, 2 represents a cache memory, 3 represents a disk controller, and 4 represents a system unit.

In FIG. 1, a disk device 1 is provided with an i-list area (shaded area) 1-1 for collectively storing data management information, and a data area 1-2 for storing data.

The cache memory 2 stores at least the data management information stored in the l-list area l-1 in the disk device FI at the time of startup.

The disk controller 3 is for controlling access to the cache memory 2 and the disk device 1 in response to access requests from the system unit 4.

[Effect]

By adopting the configuration shown in FIG. 1, the same data management information stored in the i-list area IL-1 in the disk device 1 can be quickly read from the cache memory 2. As a result, system unit 4
The average time required to complete a predetermined access process in response to an access request, such as a "read command", notified to the disk controller 3 from the disk controller 3 is shortened.

In addition, when data management information is stored in the cache memory 2, it is also stored in the i-list area of the disk device 1, so even if the power goes out, the data management information It is possible to secure greatness without losing any of the above.

〔Example〕

FIG. 2 shows a flowchart illustrating the initial setting operation performed at startup.

In the figure, ■ indicates that when the system unit 4 notifies the disk controller 3 of an "initial setting command," the disk controller 3 performs the following control.

In the figure, ■ indicates a state in which the initial settings of the disk device 1 are performed.

■ in the figure indicates the "i-list area" 1- in the disk device 1.
1 shows a state in which all data management information stored in cache memory 2 is transferred to cache memory 2.

This allows the disk device! i-list area 1-1 inside
The same data management information as that stored in the cache memory 2 will be stored in the cache memory 2.

FIG. 3 shows a flowchart illustrating operations when reading data management information and data.

In the figure, ■ indicates that when the system unit 4 notifies the disk controller 3 of a "read command," the disk controller 3 performs the following control.

In the figure, 0 indicates a state in which it is determined whether or not to read the i-list area.If YES, 9 in the figure is executed. N
In case o, execute ■ in Figure 1.

In the figure, ■ indicates a state in which designated data management information is read from the cache memory 2 and transferred to the system unit 4.

In the figure, ■ indicates a state in which designated data is read from the data area 1-2 in the disk device 1 and transferred to the system unit 4.

According to the above procedure, when reading data management information, the data management information read from cache memory 2 is transferred to system unit 4. In addition, when reading data, data area 1 in disk device 1
The data stored in -2 is transferred to system unit 4.

FIG. 4 shows a flowchart for explaining the operation when writing data management information and data.

In the figure, ■ indicates that when the system unit 4 notifies the disk controller 3 of a "write command," the disk controller 3 performs the following control.

In the figure, ■ indicates a state in which data or data management information is transferred from the system unit 4 and written to the data area 1-2 or i-list area in the disk device 1.

In the figure, [phase] indicates a state for determining whether data management information has been written to the i-list area in the disk device 1. If YES, data management information has been written to the i-list area. 2 Execute ■ in the figure. If NO, the data has been written to the data area in the disk device 1, so the series of writes ends.

■ in the figure shows a state in which the data (data management information) written to the disk device 1 is also written into the cache memory 2. As a result, the data management information stored in the i-list area in the disk device 1 is Then, the same data management information is also stored in the cache memory 2.

Through the above procedure, the data transferred from the system unit is written to the data area 1-2 in the disk device I. Further, data management information transferred from the system unit is written to the i-list area of the disk device 1 and the cache memory 2, respectively.

〔Effect of the invention〕

As explained above, according to one aspect of the present invention, a cache memory is provided and all data management information stored in the "i-list area" in the disk device is stored in the cache memory at startup, and When there is a request to read data management information from the host, the data management information stored in the cache memory is controlled to be read and transferred to the host, and when there is a request from the host to write the data management information, Since the data management information is controlled to be written to both the disk device and the cache memory, for example, the time from when a "read command" is notified to when the data management information is read can be shortened. As a result, desired data can be quickly read from the disk device.

In addition, data management information is written to the cache memory and also to the disk device, so even if the power goes out temporarily, the data management information will not be lost, ensuring reliability. can.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of one embodiment of the present invention, FIG. 2 is a flowchart explaining the initial setting operation, FIG. 3 is a flowchart explaining the reading operation, and FIG. 4 is a flowchart explaining the writing operation. shows. In the figure, l is a disk device, 1-1 is an i-list area that collectively stores data management information, l-2 is a data area that stores data, 2 is a cache memory, 3 is a disk controller, and 4 is a system unit. represents. Patent Applicant Alps Electric Co., Ltd. Patent Attorney Hiroshi Mori 1) (3 others), Tohi 13 To I Fired Key Zo Series Iman 61 Country 1,! ! ν5f, Flowchart nest of 11 steps of Sumo Rei Ayu Erikawa Tru 4I ￥1

Claims (1)

[Claims] In a disk cache control method that controls data management information in a file system to be held in a cache memory and accessed, a disk device that stores data used in the file system and data management information that manages this data. and a cache memory for transferring and retaining at least the data management information stored in this disk device, and a disk controller for accessing the disk device and the cache memory, and the data stored in the disk device at startup. At least transfers and stores management information to the cache memory, and controls the transfer of the data management information read from the cache memory when a host requests this disk controller to read the data management information, or A disk cache control method characterized in that when there is a request to write data management information, control is performed to write data to a disk device and a cache memory, respectively.