JPH0239342A - Memory ensuring system for ram disk - Google Patents

Abstract

PURPOSE:To minimize the destruction of the storage contents of a RAM disk due to the break of a power supply, etc., by transferring in DMA the contents of the RAM disk to the saving area of a magnetic disk device when a CPU has no access to the RAM disk or a magnetic disk. CONSTITUTION:The storage contents of a semiconductor memory 3a is transferred in DMA to a saving area 2b' of a magnetic disk 2b under the control of an MPU 3b forming a RAM disk 3 and a magnetic disk control part 2a forming a magnetic disk device 2 when a CPU 1 has no access to the storage contents of the memory 3a forming the disk 3. Thus it is possible to obtain the contents equal to the storage contents of the disk 3 from the disk 2b even though the contents of the disk 3 are destroyed owing to the break of power supply or the hardware reset during the operation of a computer system.

Description

[Detailed Description of the Invention] [Summary] In a computer system equipped with a magnetic disk and a RAM disk as secondary storage media, the present invention relates to a RAM disk storage maintenance method for improving the storage integrity of the RAM disk. The purpose of this system is to minimize the destruction of the storage contents in the RAM disk due to power-off or hardware reset.
In a computer system equipped with a disk,
The AM disk has at least a semiconductor memory and a DMA (Di) between the semiconductor memory and the magnetic disk device.
Rect Memory Access) has an MPU that has a function of performing transfer, and under the control of this MPU and a control unit of the magnetic disk device, the storage contents of the semiconductor memory are transferred to the RAM of the magnetic disk loaded in the magnetic disk device. The CPU saves the disk storage contents.
The configuration is such that DMA transfer can be performed when the device is not accessing the semiconductor memory.

[Industrial application field]

The present invention provides a computer system equipped with a magnetic disk and a RAM disk as secondary storage media.
The present invention relates to a RAM disk storage integrity method for improving storage integrity of an M disk.

[Conventional technology]

In recent years, in computer systems used as workstations, magnetic disks and RAM disks are frequently accessed, so there is a demand for faster access.

In general, the access time of magnetic disks is relatively long, so there is a tendency for disk caches, RAM disks, etc. to be used.

A disk cache is a memory such as 5-RAM that is placed between the CPU and memory (magnetic disk), and when the CPU accesses certain data on the magnetic disk, the address and data are transferred to the 5-RAM. The access speed is increased by reading the data stored in the 5-RAM when the CPU next accesses the same data.

A RAM disk is a semiconductor memory that is logically accessed in the same way as a magnetic disk.

[Problem to be solved by the invention] When data files stored on a magnetic disk are dispersed, a disk cache loses its effect of increasing access speed, and a situation arises in which access performance is degraded instead. There is a risk.

On the other hand, RAM disks are always accessed at high speed, but when the power is turned off due to an abnormality or the hardware is reset, the stored data is destroyed and cannot be saved. It is necessary to transfer it to a magnetic disk and store it in memory.

In a conventional RAM disk, a data file that does not cause any problem even if its memory is destroyed when the power is turned off or the hardware is reset is selected, and the file is transferred to the RAM disk for use. However, in this usage, data files that require high-speed access but do not want the stored data to be destroyed cannot be transferred and stored on the RAM disk.

Therefore, with conventional RAM disks, when trying to improve the performance of a computer system, high-speed access is required, and the CPU interrupts the original processing of data files that would be a problem if the memory was destroyed. Then, the data file must be stored on the magnetic disk, which causes a problem in that processing work that must be performed by the CPU is delayed.

In a computer system that uses a RAM disk to speed up access, the present invention protects the storage contents (data) in the RAM disk, which may be destroyed due to a power cut or hardware failure during operation. , before or when the CPU accesses the RAM disk or magnetic disk,
A RAM disk storage maintenance system that allows an MPU provided in a RAM disk to perform DMA transfer to a save area for RAM disk storage contents of a magnetic disk loaded in a magnetic disk device when the CPU is not accessing semiconductor memory. The purpose is to provide

[Means to solve the problem]

Means for solving the above-mentioned problems in the present invention will be explained with reference to FIG. The disk 3 includes at least a semiconductor memory 3a and an MPU 3b having a function of performing DMA transfer between the semiconductor memory 3a and the magnetic disk device 2.
b and the control unit 2a of the magnetic disk device 2,
The storage contents of the semiconductor memory 3a can be DMA transferred to the RAM disk storage contents save area 2b' of the magnetic disk 2b loaded in the magnetic disk device 2 when the CPU is not accessing the semiconductor memory 3a. This is a storage preservation method for RAM disks.

[Effect]

By the means described above, before or when the CPUI accesses the storage contents (data) of the semiconductor memory 3a forming the RAM disk 3, the RA
Under the control of the MPU 3b forming the M disk 3 and the control unit 2a forming the magnetic disk device 2, the storage contents of the semiconductor memory 3a are saved to the RAM disk storage contents of the magnetic disk 2b loaded in the magnetic disk device 2. By transferring DMA to area 2b', even if the memory contents of the RAM disk are destroyed due to a power cut or hardware reset during computer system operation, the same memory contents can be preserved on the magnetic disk. You can leave it there.

〔Example〕

FIG. 1 is a block diagram of the first embodiment of the present invention, where l is CP
Reference numeral 2 denotes a magnetic disk device, which includes a control section 2a formed of, for example, an MPU, and a loaded magnetic disk 2b.

3 is a RAM disk, which has at least a semiconductor memory 3a and an MPU 3b having a function of performing DMA transfer between the semiconductor memory 3a and the magnetic disk 2b loaded in the magnetic disk device 2; MPU
3b and the control unit 2a of the magnetic disk device 20, the storage contents (data) of the semiconductor memory 3a are transferred to the RA of the magnetic disk 2b loaded in the magnetic disk device 2.
It is designed to enable DMA transfer to the save area 2b' for the contents stored in the M disk.

Note that 3c is a working register constituting the RAM disk 3, which is used to transfer data from the semiconductor memory 3a to the magnetic disk 2b.
It stores an address at the time of transferring the stored contents of the RAM disk to the save area 2b', and a detailed explanation of its operation will be described later. 4 is the main memory of the CPU10.

Next, to explain its operation, before the CPUI accesses the storage contents of the semiconductor memory 3a that forms the RAM disk 3, the working register 3 that forms the RAM disk 3
In c, the CPU writes the start address of the save area 2b' for the RAM disk storage contents on the magnetic disk 2b. After writing, the CPUI uses this RAM disk in the same way as a normal magnetic disk (how to use a normal RAM disk).

In the RAM disk 3, the MPU 3b monitors the writing of data from the CPU 1 to the semiconductor memory 3a, and checks whether valid data is stored in the semiconductor memory 3a.
After the PU 3b confirms, when the CPU 1 is not accessing the data stored in the semiconductor memory 3a, the data is transferred to the save area 2b' of the magnetic disk 2b by the MPU 3b.
and is written under the control of the control unit 2a of the magnetic disk device 2.

FIG. 2 is a block diagram of a second embodiment of the present invention, in which, in addition to the above-mentioned components of the RAM disk 3, there is also a bus receiver 3d for receiving address signals from the bus 5, and a bus receiver 3d for outputting address signals to the bus. The bus driver 3e is added to the bus driver 3e, and an address decoder/access monitoring circuit 3f that decodes the address signals of the entire bus and monitors data access from the CPUI to the semiconductor memory 3a.

This address decoder/access monitoring circuit 3f has the following functions. That is, when it is confirmed that the semiconductor memory 3a has been selected by monitoring the address signals of the entire bus, a selection signal is input to the semiconductor memory 3a to put the semiconductor memory 3a into a write/read state, and the work register 3c is When it is confirmed that the selection has been made, the selection signal is input to the working register 3c and the selection signal is input to the working register 3c.
c, the storage state is set to the start address of the save area of the RAM disk storage contents and the next transfer destination address.

It also monitors whether the CPUI is writing data to the semiconductor memory 3a or reading data from the semiconductor memory 3a.

As shown in FIG. 3, the work register 3c has a first
The first register 3c contains the start address of the save area and whether the address is valid (bit 1) or invalid (bit 0).
) bits are stored. Further, the second register 3cz is configured such that access between the semiconductor memory 3a forming the RAM disk 3 and the magnetic disk 2b is controlled by the CPU.
Stores the address for the next data transfer (next transfer destination address) when the access is interrupted by an access from.

Writing of the start address of the save area to the first register 3c as described above is performed by the CPUI, and is read-only from the MPU 3b forming the RAM disk 3. Further, only the MPU 3b forming the RAM disk 3 performs writing/reading (reading/writing) of the next transfer destination address to the second register 3cz.

When the CPUI writes the start address of the save area to the first register 3c forming the working register 3c,
Always set the bit to 1. The MPU3b selects this bit 1.
If the bit is not 1, it is determined that the save area is not prepared, and data is not saved from the semiconductor memory 3a to the save area 2b' of the RAM disk storage contents of the magnetic disk 2b by DMA.

A first register 3c forming the working register 3C
This RAM disk 3, in which the start address of the save area is stored together with the valid bit, issues a bus access request to the CPU 1. When the CPUI is not using the bus, CP[Jl grants the RAM disk 3 permission to use the bus, and the RAM disk 3 starts accessing the magnetic disk device 2 by DMA. In this case, normal DMA access can use the bus with priority over the CPU, but the bus usage priority of this RAM disk 3 is set lower than that of the CPUI. This allows the CPU
The RAM disk 3 uses the bus during the time when I is not using the bus, and it is possible to prevent the performance of the computer system from deteriorating.

FIG. 4 shows a DMA (DwXi approximate time chart) between the RAM disk 3 and the magnetic disk device 2.

As shown in this figure, CPUI is connected to RAM disk 3.
Or, if you are accessing the magnetic disk 2b, R
Even if there is an access request to the magnetic disk 2b in the AM disk 3, the RAM disk 3 will not be able to access the magnetic disk 2b.
DMA cannot be performed on b.

While the RAM disk 3 is accessing the magnetic disk 2b,
When the CPUI access starts, wait for the end of the current access, and then store the address for the next access (next transfer destination address) in the second register 3ct forming the working register 3c. , RAM disk 3 interrupts DMA. When the CPUI no longer uses the bus 5, the RAM disk 3 is transferred to the second register 3ct.
from the next transfer destination address stored in the magnetic disk 2b.
DMA is restarted to the save area 2b'.

〔Effect of the invention〕

As explained above, according to the present invention, in a computer system equipped with a RAM disk for speeding up access and a magnetic disk device that is relatively slow in access but is unpredictable, power is cut off during operation. RA whose memory may be destroyed by resetting or hardware reset
The storage contents in the M disk are loaded into the magnetic disk device under the control of the MPU provided in the RAM disk and the control unit of the magnetic disk device before or when the CPU accesses the RAM disk or magnetic disk. DMA transfer can be performed to the save area of the RAM disk storage contents of the magnetic disk, which can minimize the destruction of data in the RAM disk.
It has the effect of improving the integrity of data in the AM disk, and since all data files that require high-speed access to software can be stored on the RAM disk, it is possible to optimally speed up the computer system. This greatly contributes to improving the performance of computer systems.

3d...Bass receiver 3e・・・Bus driver 3r...address decoder 4...Main memory, 5...Bus.

・Access monitoring circuit,

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the first embodiment of the present invention, Fig. 2 is a block diagram of the second embodiment of the present invention, Fig. 3 is a diagram showing an example of a working register, and Fig. 4 is an access time chart. It is. 1...CPU. 2... Magnetic disk device, 2a... Control unit, 2b... Magnetic disk, 2b'... Save area for RAM disk storage contents, 3.
...RAM disk, 3a...semiconductor memory, 3b...MPU. 3c...Work register,

Claims (1)

[Claims] A CPU (1) and a magnetic disk device (as a secondary storage medium)
In a computer system equipped with a RAM disk (2) and a RAM disk (3), the RAM disk (3) includes at least a semiconductor memory (
3a) and an M having a function of performing DMA transfer between the semiconductor memory (3a) and the magnetic disk device (2).
Under the control of this MPU (3b) and a control unit (2a) of the magnetic disk device (2), the storage contents of the semiconductor memory (3a) are transferred to the magnetic disk device (2). The CPU (1) saves the RAM disk storage contents of the magnetic disk (2b) loaded into the
1. A RAM disk storage preservation system characterized in that DMA transfer can be performed when the semiconductor memory (3a) is not being accessed by the RAM disk.