JPH0527913A - Optimizing method for buffer ratio - Google Patents

Abstract

PURPOSE:To provide a means to improve efficiency for using a bus by changing the value of a buffer ratio in an external storage device. CONSTITUTION:This control method of the external storage device adopts a zone bit recording system to designate the buffer ratio for controlling the occupying time of a bus 16 in the case of an input/output processing from a host device 11, to perform access, to divide a magnetic disk medium 13 into plural zones in a circumferential direction and to change write density for each ratio and by changing the buffer ratio in the external storage device corresponding to the zone storing accessed data, data transfer is continuously executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of optimizing a buffer ratio used in a magnetic disk device. An object of the present invention is to divide a magnetic disk medium into a plurality of zones in the circumferential direction and change the write density for each zone.
This is an improvement in bus usage efficiency in the external storage device that employs the recording method.

In recent years, there has been a demand for large capacity and high speed of computer systems, and an external storage device adopts a zone bit recording method to achieve a large capacity.
In the system, the capacity is increased by connecting a plurality of external storage devices to the host device. For this reason, multiple devices are connected to the bus, and the efficiency of the entire system cannot be improved unless the bus usage efficiency of each device is improved.

[0003]

2. Description of the Related Art Therefore, by providing a buffer memory in a magnetic disk device, data transfer can be concentrated and bus usage efficiency can be improved. In addition, for the buffer memory, a function to specify the buffer ratio indicating how much data was accumulated in the buffer from the host device and improve the bus usage efficiency was provided.
In an external storage device that uses the zone bit recording method, the transfer rate differs for each zone.
It is necessary to avoid this because if the specified fixed value from the host device is used, the bus usage efficiency will vary depending on the access position from the host device, and the bus usage efficiency may not be good.

FIG. 5 is a block diagram of a conventional zone bit recording type external storage device. In the figure,
Reference numeral 11 is a host device which issues a write / read command to an external storage device, 12 is a buffer memory for temporarily storing data read from the medium, 13 is a disk medium for recording data, 1
Reference numeral 4 is a buffer ratio designating circuit that designates the overall ratio of the amount of data stored in the buffer memory, 15 is a control unit that controls the external storage device, and 16 is a bus that connects the host device 11 and the external storage device. The operation in FIG. 5 will be described. The higher-level device 11 specifies the head block address in which the data to be read is stored together with the buffer ratio at the time of data transfer. The external storage device stores the buffer ratio in the buffer ratio designating circuit 14 and the address in the address register 17. The control unit 15 of the external storage device sequentially reads the designated data blocks from the disk medium 13 and the buffer memory 12
Accumulate in. When the data is accumulated in the buffer memory 12 until the designated buffer ratio is reached, the control unit 15 notifies the host device 11 of an interrupt for data transfer, and after the acknowledgment of the interrupt, starts the data transfer.

FIG. 4 is a time chart of an interface with a conventional zone bit recording type magnetic disk device. Since the number of bits per unit angle can be increased outside the disk medium, the bit rate is high, and inside the disk medium, the bit rate is low. Therefore, the recording area of the medium is divided into an outer zone and an inner zone to change the recording density. In the figure, (A) is the waveform of reading from the outer medium, and (B) is the inner reading waveform. Data is read from the medium and stored in the buffer memory at this bit rate. When reading, the buffer ratio specifies the full amount of data stored in the buffer memory, so the buffer full ratio (Buffer Full Rait
The buffer empty ratio (Buffer Empty Rat) is used to specify the amount of free space to store the transfer data from the host device in the buffer memory when writing.
io) is called.

The buffer ratio is set so that data transfer is started when two blocks enter the buffer memory.
In the outer zone, the bit rate of reading from the medium is faster than the bit rate of data transfer with the host device, so that the data transfer with the host device can be completely transferred without interruption. (C) of the figure is a time chart of data transfer at this time.

However, in the inner zone, the bit rate of reading from the medium is slower than the bit rate of data transfer with the host device, so that data to be transferred with the host device is not stored in the buffer memory during data transfer with the host device. Therefore, the processing is interrupted, and the transfer is restarted after the second block is entered in the buffer memory again. (D) of the figure is a time chart of data transfer at this time. In this way, once interrupted, an interrupt is notified again to use the bus and the processing is performed, so extra processing time is required and the bus usage efficiency decreases. Therefore, it is desirable from the viewpoint of bus usage efficiency to transfer all necessary data without interruption of data transfer.

[0008]

As described above, in the zone bit recording type external storage device, there is a problem that the setting of the buffer ratio from the host device does not match the actual condition.

According to the present invention, in an external storage device adopting the zone bit recording method, which zone is determined from the access position from the host device regardless of the buffer ratio value designated by the host device. The purpose is to provide a means to improve the bus usage efficiency by changing the buffer ratio value inside the external storage device.

[0010]

The above-mentioned problems can be solved by a buffer ratio optimizing method configured as follows. FIG. 1 is a principle diagram of the present invention.

The magnetic disk medium 13 is divided into a plurality of zones in the circumferential direction and is accessed by designating a buffer ratio for controlling the occupation time of the bus 16 at the time of input / output processing from the host device 11 and writing density for each zone A method of controlling an external storage device that employs a zone bit recording method in which the buffer ratio is changed within the external storage device according to the zone in which the accessed data is stored. Thus, the data transfer is continuously performed.

[0012]

The data transfer is continued by changing the buffer ratio inside the external storage device according to the zone in which the accessed data is stored.

[0013]

FIG. 2 is a block diagram of an embodiment of the present invention. In the figure, numeral 17 is an address register for designating the position on the disk of a data block to be accessed, and other elements having the same reference numerals as those in FIG.

The operation in FIG. 2 will be described. Host device 11
Specifies the start block address where the data to be read is stored together with the buffer ratio at the time of data transfer. The external storage device has a buffer ratio designating circuit.
In 14, the address is stored in the address register 17. The control unit 15 of the external storage device looks at the designated address register 17, determines whether it is the inner zone or the outer zone, and determines the data transfer rate from each disk medium 13, the bus data transfer rate, and the total data transfer rate. The buffer ratio is determined from and the value is set in the buffer ratio designating circuit 14. After that, the control unit 15 of the external storage device sequentially reads the specified data blocks from the disk medium 13 and the buffer memory 12
Accumulate in. When the data is accumulated in the buffer memory 12 until the set buffer ratio is reached, the control unit 15 notifies the host device 11 of an interrupt for data transfer, and starts data transfer after the acknowledgment of the interrupt.

FIG. 3 shows a zone bit of the embodiment of the present invention.
3 is a time chart of an interface with a recording type magnetic disk device. FIG. 3 (E) is a time chart in the case of the outer zone. (A) is a time chart for reading from the medium, which is the same as FIG. Here, since the data transfer rate of the bus is slower than the data transfer rate from the medium, the data transfer is started immediately after the minimum amount of one block is accumulated in the buffer memory 12, and eight blocks are transferred without interruption. Figure 3 (F) is for the inner zone,
4B is a time chart for reading from the medium, which is the same as FIG. Since the data transfer rate from the medium is slower than the data transfer rate of the bus on the inside, 3 blocks are stored in the buffer memory 12 in order to transfer 8 blocks, and 8 blocks are transferred without interruption by starting the data transfer. be able to.

Thus, when the data transfer rate from the medium is slower than the data transfer rate of the bus, the minimum storage amount of the buffer memory for performing the transfer without interruption from the two data transfer rates and the total data transfer rate. Is determined.

Therefore, if such a determination is made every time a data transfer instruction is given from the host device and the buffer ratio is changed, the bus usage efficiency is improved.

[0018]

As described above, according to the present invention,
In an external storage device that uses the zone bit recording method, it is possible to improve bus utilization efficiency by changing the buffer ratio value inside the external storage device from the access position (zone) from the host device. it can.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of an embodiment of the present invention.

FIG. 3 is a time chart showing the operation of the embodiment of the present invention.

FIG. 4 is a time chart showing a conventional operation.

FIG. 5 is a block diagram of a conventional external storage device for zone bit recording.

[Explanation of symbols]

11 host device 12 buffer memory 13 disk medium 14 buffer ratio designation circuit 15 control unit 16 bus 17 address register 20 zone determination circuit

Claims (1)

What is claimed is: 1. A bus (1) for input / output processing from a host device (11).
6) Access by setting the buffer ratio designating circuit (14) that designates the buffer ratio for controlling the occupation time,
A zone bit that divides the magnetic disk medium (13) into multiple zones in the circumferential direction and changes the write density for each zone.
A method for controlling an external storage device that employs a recording method, wherein data transfer is continued by changing the buffer ratio inside the external storage device according to the zone in which the accessed data is stored. A method for optimizing a buffer ratio, which is characterized by: