JPH0664772B2 - Controller for magnetic tape unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a magnetic tape device capable of continuously recording / reproducing data blocks (executable in streaming mode).
The present invention relates to a control method of a magnetic tape device for automatically adjusting a channel load of an information processing system incorporating the above as one of system configurations.

(B) Background of Technology Various studies have been made so that a large amount of data can be transferred at a time when data is transferred between a magnetic tape device and a main storage device. That is, the methods that allow a large amount of data to be transferred within a specified time are roughly classified into (1) a method for improving the recording density of the magnetic tape and (2) a method for improving the running speed of the magnetic tape.

The magnetic tape running method by the streaming mode has been put into practical use as a method for realizing a large amount of data transfer at low cost. That is, the magnetic tape running at a constant speed is processed at a high speed, but a motor with a slow rising / falling (start / stop) speed is used to avoid the rising and falling times as much as possible, and data is seamlessly recorded. By transferring the data, a large amount of data can be transferred. Further, the motor becomes more expensive as the rising / falling (start / stop) speed becomes steeper.

On the other hand, when constructing an information processing system, the magnetic tape running method by the streaming mode may not always be an effective feature from the viewpoint of the overall balance of the information processing system. There has been a demand for the practical application of a control method whose features effectively act in constructing an information processing system.

(C) Related Art and Problems Next, a conventional magnetic tape device control method will be described with reference to the drawings.

FIG. 1 shows a schematic diagram of conventional magnetic tape control.

In the figure, 1 is a main memory (MEM), 2 is a channel device, 3 is a channel controller (hereinafter referred to as CHC),
4 to 6 are block multiplexer channels (hereinafter referred to as BMC), 7 is a magnetic tape controller (hereinafter referred to as MTC), 8 is a magnetic tape device, 9 is a magnetic disk controller (hereinafter referred to as DKC), and 10 is a magnetic disk. Each device is shown.

FIG. 1 shows a main storage device 1, a main storage device 1 for storing data transferred from an input / output device (such as a magnetic tape device 8 and a magnetic disk device 10) and an input / output device (magnetic tape device 8) connected thereto. Is a channel device 2 for controlling data transfer between magnetic disks 10 and the like, a CHC 3 for controlling data in the channel device 2, and a plurality of input / output devices (such as the magnetic tape device 8 and the magnetic disk device 10) for data transfer. BMC4 ~ 6 to operate the operation, MTC7 to selectively control the data transfer operation of the plurality of connected magnetic tape device 8, magnetic tape device 8 adopting the magnetic tape running system by streaming mode, connected It is composed of a DKC 9 for selectively controlling data transfer operations of a plurality of magnetic disk devices 10 and a magnetic disk device 10 having a disk-shaped recording medium.

When data is transferred between the main recording device 1 and an input / output device (such as the magnetic tape device 8 or the magnetic disk device 10) in the system configured in FIG. 1, the connected magnetic tape device 8
Generally, the system is constructed so that the load of the set data transfer pulse (connection path) from the magnetic disk 10 or the like to the main storage device 1 is balanced. That is, the system is constructed so that both the data transfer request from the magnetic tape device 8 and the data transfer request from the magnetic disk device 10 are processed as uniformly as possible to satisfy the request degree.

On the other hand, the magnetic tape running method by the streaming mode is characterized in that once the magnetic tape running is started, the magnetic tape running is continuously performed at a high speed without stopping the magnetic tape running. In such a case, the channel load (path load) related to the data transfer of the magnetic tape device 8 becomes high. Therefore, although the work related to the magnetic tape device 8 is efficiently executed, there arises a problem that the responsiveness from the input / output device having a different data transfer form such as the magnetic disk device 10 is suppressed.

Further, from the viewpoint of one side of the system operation, since it is premised that the input / output requests to the magnetic tape device 8 are continuously issued, the backup mode of the magnetic disk device 10 depends on the streaming mode. It can be said that the magnetic tape running method is suitable.

However, when backup processing is performed by the magnetic disk device 10 and the magnetic tape device 8, the streaming continuation state is (1) effective read efficiency of the magnetic disk 10 and (2) an intermediate buffer memory (in the main storage device 1). (3) The capacity of the backup buffer memory) and the data transfer speed of the magnetic tape device 8 are combined and determined substantially automatically. This means that when dumping an unspecified number of data,
There is a problem that the streaming continuation state is unpredictable.

(D) Object of the Invention The present invention aims to provide a novel control method for a magnetic tape device that solves the above-mentioned problems, and in particular, even if the streaming operation continues for a long time, a predetermined continuation is performed. It is to realize a control method for a magnetic tape device that can stop the streaming operation in this state and prevent an abnormal increase in path load.

(E) Configuration of the Invention In the present invention, in a magnetic tape device for recording / reproducing data on a magnetic tape in block units, the data recording / reproducing process is continuously executed for any number of data blocks. Counting means for counting the number of times, storage means for storing the threshold value of the count value given by a command from the host device, and comparison for comparing the count value in the counting means with the threshold value stored in the storage means. Means is provided, and if the comparison result of the comparison means does not match, the data block recording / playback processing is subsequently executed, and if the comparison result is match, the data block recording / playback processing is stopped. Achieved by a control device of a magnetic tape device, characterized by preventing an abnormal rise of a data transfer path (connection path) set between the magnetic tape device and the host device. Can be achieved.

(F) Embodiments of the Invention The present invention will be described below with reference to the drawings.

FIG. 2 shows a control schematic diagram of the magnetic tape device according to the present invention, and FIG. 3 shows an embodiment of the magnetic tape control according to the present invention.

In the figure, 8'and 8 "are magnetic tape devices, 11 is an interface unit, 12 is a control unit, 13 is a logical sum circuit, 14
Is a threshold counter circuit, 15 is a streaming counter circuit, and 16 is a comparison circuit.

The same symbols as in FIG. 1 indicate the same contents, or threshold set signal, is threshold information, is streaming continuation signal,
Shows a streaming interruption signal, shows a streaming continuation permission signal, and shows a streaming continuation prohibition signal, respectively.

This embodiment shown in FIG. 2 is the channel device 2, CHC3, BMC4 to 6, MTC7, magnetic tape device 8 and magnetic tape device 8'having the same function as the magnetic tape device 8 described in FIG.
8 ", an interface unit 11 in the MTC7 for sharing the interface function with the BMCs 4 to 6, and a control unit 12 in the MTC7 for controlling the data input / output of a plurality of magnetic tape devices 8, 8 ', 8". It consists of The control unit 12 shown in FIG. 3 stores a logical sum circuit 13 that takes a logical sum condition between a threshold value set signal and threshold value information given by a command from a higher-level device (not shown), and the maximum allowable number of continuous streaming numbers. The output of the streaming counter circuit 15 and the output of the streaming counter circuit 15 are compared with the output of the streaming counter circuit 15, which is stepped by the streaming continuation signal generated by the control unit 12 itself and reset by the streaming interruption signal. And a comparison circuit 16 that outputs a streaming continuation permission signal when they do not match and outputs a streaming continuation prohibition signal when they match.

Next, the operation of this embodiment will be described. The number of streaming continuations means the number of data blocks (not shown) that divide the magnetic tape (not shown).
Count whether there is continuous processing. That is, the number of continuous streaming is counted as (n-1) times when the data recording / reproducing process is continuously performed on n data blocks (not shown).

When the magnetic tape device 8, 8 ', 8 "adopting the magnetic tape running method in the streaming mode is incorporated in the system, the maximum allowable number of continuous streaming numbers determined in advance in consideration of the system configuration contents is set to the upper device. (Not shown) is stored in the threshold value counter circuit 14 by a command via BMC 4 to 6. In this state, the magnetic tape device 8
When there is a data transfer request to the main memory device 1, the channel device 2 controls to form a data transfer path with the main memory device 1, and when the data transfer path is formed, the main memory device 1 and the magnetic tape device 8 are connected. Data is transferred between.

The MTC 7 counts the streaming continuation signal by the streaming counter circuit 15 and continues the data transfer until it matches the threshold value stored in the threshold value counter circuit 14. If the count value of the streaming counter circuit 15 matches the threshold value, the comparison circuit A streaming continuation prohibition signal from 16 is output. The MTC 7 reports the streaming continuation prohibition signal to the higher-level device (not shown) via the BMCs 4 to 6 with a retry status. The host device (not shown) that has received the streaming continuation prohibition signal sends a streaming interruption signal to the streaming counter circuit 15 via the MTC7 to reset the count value of the streaming counter circuit 15 up to that point.

(G) Effects of the Invention According to the present invention as described above, even if the streaming operation continues for a long time, the streaming operation is terminated at a predetermined number of times to prevent an abnormal increase in the path load. There is an effect that it is possible to provide a possible control system of the magnetic tape device.

[Brief description of drawings]

FIG. 1 is a schematic diagram of conventional magnetic tape control, FIG. 2 is a schematic diagram of control of a magnetic tape device according to the present invention, and FIG. 3 is an embodiment of magnetic tape control according to the present invention. In the figure, 1 is a main memory device (MEM), 2 is a channel device, 3 is a CHC, 4 to 6 are BMCs, 7 is an MTC, 8, 8 ', 8 ".
Is a magnetic tape device, 9 is a DKC, 10 is a magnetic disk device, 11 is an interface unit, 12 is a control unit, 13 is an OR circuit, 14 is a threshold counter circuit, 15 is a streaming counter circuit, and 16 is a comparison circuit. .

Claims (1)

[Claims] 1. A controller of a magnetic tape device for recording / reproducing data on a magnetic tape in block units, how many times the data recording / reproducing process has been continuously executed. Counting means for counting
Storage means for storing the threshold value of the count value given by a command from the host device and comparison means for comparing the count value in the counting means with the threshold value stored in the storage means are provided. If the comparison results do not match, the data block is continuously recorded / recorded on the magnetic tape device.
A control device for a magnetic tape device, wherein a reproducing process is executed, and when the comparison result is a match, the magnetic tape device stops the recording / reproducing process of the data block.