JP2000311064A - Control system for buffer in data transfer controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the efficiency of data transfer by performing data transfer control on the basis of the driving condition of a magnetic tape recorder which includes the buildup time until an accumulation quantity of buffer data and magnetic tape recorder reach a stationary speed. SOLUTION: In a main control part 15, it is judged whether data should be written to a magnetic tape recorder 120 from a buffer 11 by using a data transfer time, a total amount of data existing in the buffer 11 at that moment, the buildup time of the magnetic recorder 120 and information stored in a storage part 14. When the condition for writing is met, the main control part 15 drives the magnetic tape recorder 120 and starts a second timer 13. When the magnetic tape recorder 120 is completely activated, the timer value of the second timer 13 is read and stored in a storage part 14. the storage part 14 holds this value and feeds it back to the writing condition. In this way, data transfer control is performed on the basis of the driving condition of the magnetic tape recorder 120.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buffer control method in a magnetic tape control device, and more particularly, to a buffer control method in a magnetic tape control device capable of performing data transfer efficiently without stopping data transfer. Related to the control method.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing an example of a buffer control method in a conventional magnetic tape control device used as an external storage device of a large computer. As shown in FIG. 8, this method uses a host device 100 that sends data.
And a magnetic tape control device 110 for controlling the magnetic tape recording device 120. The magnetic tape control device 110 includes a buffer 111 for temporarily storing data from the higher-level device 100, and these components 100, 11
It is composed of a main control unit 112 for controlling 1, 120.

[0003] These components 100, 111, 120
Operate as follows. Host device 10
0 transmits a command to the main control unit 112. Upon receiving the command, the main control unit 112 transfers data from the host device 100 to the buffer 111. The buffer 111 stores the received data. The main control unit 112 determines conditions for driving the magnetic tape recording device (magnetic tape recording device driving conditions), transfers data from the buffer 111 to the magnetic tape recording device 120,
The magnetic tape recording device 120 is driven.

FIG. 9 is a flowchart showing the operation of the buffer control system having the above-described configuration. First, the host device 100
Transmits a command to the main control unit 112. Main control unit 11
2 starts data transfer from the host device 100 to the buffer 111 (step A1). The main control unit 112 determines the write condition while observing the amount of data in the buffer 111 (step A2). If the driving condition of the magnetic tape recording device 120 is not satisfied (step A2, no),
It returns to step A1 again. If the magnetic tape recording device drive condition is satisfied (step A2, YES), data transfer from the buffer 111 to the magnetic tape recording device 120 is started (step A3).

If the buffer 111 is already full (step A4, Yes), the host device 100
Then, the data transfer to the buffer 111 is stopped (step A7). If the buffer 111 is not full and the buffer 111 is not empty, the buffer 11
1 to the magnetic tape recording device 120 (step A5, No). If the buffer 111 is empty (step A5, Yes), the magnetic tape recording device 1
20 is stopped (step A6). If the main control unit 112 has a command from the host device 100,
The main control unit 112 transfers data from the host device 100 to the buffer 111 (return to step A1). If there is no command in the main control unit 112 (step A8, No), the magnetic tape control device 110 ends the operation.

[0006]

However, this prior art has the following problems. That is, the buffer 111
Since the drive condition of the magnetic tape recording device is constant, the transfer speed from the host device 100 fluctuates, so that the buffer 111 is easily filled up and the buffer 111 becomes empty, and the magnetic tape recording device 120 is stopped (step A).
6) Also, data transfer from the higher-level device 100 stops frequently (step A7), and the efficiency of transferring data from the higher-level device 100 to the magnetic tape recording device 120 via the buffer 111 is reduced.

Accordingly, an object of the present invention is to provide a magnetic recording apparatus capable of efficiently transferring data without stopping data transfer when transferring data from a host device to a magnetic tape recording device via a buffer. An object of the present invention is to provide a buffer control method in a tape control device.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a data transfer control device for writing data held by a host device to a magnetic tape recording device via a buffer provided in the data transfer control device. In the control method, the data transfer control is performed based on a drive condition of the magnetic tape recording device including a storage amount of data in the buffer and a rise time until the magnetic tape recording device reaches a steady speed. .

With this configuration, fine adjustment can be performed based on the driving conditions of the magnetic tape recording apparatus, including the amount of data stored in the buffer and the fluctuation factors such as the rise time until the magnetic tape recording apparatus reaches a steady speed. Since the data transfer control is performed while the data transfer is being performed, the data transfer can be efficiently performed without stopping the data transfer.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiment. Note that the same reference numerals are given to the already described portions, and redundant description is omitted.

[I] First Embodiment Referring to FIG. 1, this embodiment is roughly divided into a high-order device 100 for sending data, a magnetic tape control device 10 for controlling a magnetic tape recording device 120, and a magnetic tape recording device. It comprises the device 120.

The magnetic tape control device 10 includes a host device 10
A buffer 11 for temporarily storing data from 0;
A first timer 12 for measuring a data transfer time forming a "first monitoring means" and a second timer 13 for measuring a rise time of a magnetic tape recording device 120 forming a "second monitoring means"
A storage unit 14 for storing the measured value of the second timer 13 and the amount of data in the buffer 11;
00, 120, 11, 12, 13, and 14 are provided. Here, the rise time of the magnetic tape recording device 120 refers to a time required to reach a steady speed required for stably recording data.

These components 100, 120, 11,
12, 13, and 14 operate as follows. The host device 100 transmits a command to the main control unit 15. The main control unit 112 that has received the command causes the host device 100 to transfer data to the buffer 11. The buffer 11 stores the received data. At this time, the first timer 12 measures the transfer time, and the main control unit 15
Notify. The main control unit 15 obtains the value of the storage unit 14 and the data amount from the buffer 11, determines the transfer of data from the buffer 11 to the magnetic tape recording device 120, and drives the magnetic tape recording device 120. At this time, the second timer 13 measures the time when the magnetic tape recording device 120 starts up, notifies the main control unit 15 and stores the value in the storage unit 14.

(1) Schematic Operation of the Present Embodiment In FIGS. 1 and 2, when the host device 100 sends a write command to the main control unit 15, the main control unit 15 that has received the command transmits the write command from the host device 100. The received write data is transferred to the buffer 11 (step S
1). At this time, the main control unit 15 measures the transfer time of a certain amount of data using the first timer 12 (Step S).
2).

The main control unit 15 stores the data transfer time, the total amount of data existing in the buffer 11 at that time (the amount of data in the buffer), the rise time of the magnetic tape recording device 120, and the storage unit 14. It is determined whether data is to be written from the buffer 11 to the magnetic tape recording device 120 using the information (described below) (step S).
3).

When the condition for writing (drive condition of the magnetic tape recording device) is satisfied (step S3, Yes), the main controller 15 drives the magnetic tape recording device 120 and starts the second timer 13 (step S3). S4). When the magnetic tape recording device 120 has completely started up (step S5, Yes), the timer value of the second timer 13 is read and stored in the storage unit 14 (step S6). The storage unit 14 holds this value and feeds it back to the writing condition (magnetic tape recording device driving condition) (Step S
7).

By providing the buffer 11, the first timer 12, the second timer 13, and the storage unit 14 in this manner, the conditions for driving the magnetic tape recording device 120 (the magnetic tape recording device driving conditions) are finely adjusted. Tape recording device 12
It is possible to reduce the loss of the time from the start of 0 to the complete startup and to write data at high speed (step S8).

(2) Detailed Operation Next, the overall operation of the present embodiment will be described in detail with reference to the flowcharts of FIGS.

First, the host device 100 transmits a command to the main control unit 15. The main control unit 15 starts data transfer from the host device 100 to the buffer 11 (step A1 in FIG. 3). Next, the first timer 12 is started (step A2). Next, when a certain amount of data is transferred into the buffer 11 (step A3, YES), the first timer 12 is read (step A4), and the value of the first timer 12 and the data amount of the buffer 11 are read. To determine the drive of the magnetic tape recording device (determination of the drive condition of the magnetic tape device) (step A5). If a certain amount or more of data has not been transferred (step A3, No), the process returns to step A3 without stopping the first timer 12 until a certain amount or more of data is transferred again.

Here, the driving conditions of the magnetic tape recording device will be exemplified. The size of the buffer 11 is B kilobytes.
Further, the data transfer amount serving as a read condition of the first timer 12 is d kilobytes, the timer value at that time is T milliseconds, and the rise time of the magnetic tape recording device 120 is D milliseconds. The main controller 15 obtains from the buffer 11 that the data amount is b kilobytes. Assuming that D millisecond data is continuously transferred while maintaining the current data transfer speed, the amount of data predicted to be transferred from the higher-level device 100 is {d (kilobytes) ÷ T (milliseconds) ×
D (milliseconds)}, the driving condition of the magnetic tape recording device is {d (kilobytes) {T (milliseconds) × D (milliseconds) + b (kilobytes) ≧ B}.

If the magnetic tape recording device driving conditions are not satisfied (step A5, NO), the process returns to step A1. If the magnetic tape recording device drive condition is satisfied (step A5, Yes), the main control unit 15 sets the data amount in the buffer 11 at this time in the storage unit 14 (step A6), and sets the second timer 13 to Then, the magnetic tape recording device 120 is driven. Magnetic tape recording device 1
If 20 has completely started (step A8, YES), the value of the second timer 13 is read, and the value of the second timer 13 is notified to the storage unit 14 (step A9). To start data transfer (step A10).

If the buffer 11 is full (step A11, Yes), the data transfer from the host device 100 to the buffer 11 is stopped (step A1).
4) Also, the buffer 11 is not full and the buffer 11
Is not empty (step A12, No), the data transfer from the buffer 11 to the magnetic tape recording device 120 is performed (step A10). If the buffer 11 is empty, the magnetic tape recording device is stopped (step A).
13). If the main control unit 15 has a command from the host device 100 (step A15, Yes), the main control unit 1
5 transfers data from the host device 100 to the buffer 11 (return to step A1). If there is no command in the main control unit 15 (step A15, No), the magnetic tape control device 10 ends the operation.

(3) Specific Example Next, a specific example will be described with reference to the flowcharts of FIGS. 1 and 3 and FIGS. 4, 5, and 6.

First Specific Example In this specific example, as shown in FIG. 4, there is a sufficient capacity for storing data in the buffer 11.

As shown in FIG. 3, the main control unit 15 which has received the data from the higher-level device 100 to write the data,
From 00, data is transferred to the buffer 11 (step A1), and the first timer 12 is started (step A2). Here, as shown in FIG. 4, it is assumed that the size of the buffer 11 is 500 kilobytes (B = 50
0). Further, the data transfer amount serving as a reading condition of the timer is set to 5 kilobytes (d = 5).
20 with a rise time of 100 ms (D =
100). From the above values, the driving condition of the magnetic tape recording device is {5 (kilobytes) {T (milliseconds) × 100 (milliseconds) + b (kilobytes) ≧ 500}.

After fixing this condition, the first timer 12 is read each time 5 kilobytes of data are transferred from the host device 100 to the buffer 11 (step A4). For example, it is assumed that the data is transferred to the buffer 11 up to 100 km (b = 100), and then the first timer 12 is read (step A3). Here, assuming that the value of the first timer 12 is 5 milliseconds (T = 5) (step A).
4), assuming that 100 milliseconds of data are continuously transferred while maintaining the current data transfer rate (the prediction line in FIG. 4), {5 (kilobytes)} 5 (milliseconds) × 100
(Milliseconds) +100 (kilobytes) = 200 (kilobytes) <500 °, so that the magnetic tape recording device driving condition is not satisfied (step A5, no). Therefore, the data transfer from the host device 100 to the buffer 11 is continuously performed (step A1).

Second Specific Example In this specific example, as shown in FIG. 5, the buffer 11 is expected to become full soon.

Next, as shown in FIG. 5, consider the case where 400 kilobytes of data are stored in the buffer 11 (b).
= 400). Assuming that the timer value at this time is also 5 milliseconds, the driving condition of the magnetic tape recording apparatus is as follows (predicted line in FIG. 5): (5 (kilobytes) ÷ 5 (ms) × 100 (ms) +400 ( Kilobytes) = 500 (kilobytes)
Since it is predicted that the rise time of the magnetic tape recording device 120 has expired from ≧ 500 °, the buffer 11 is expected to be full at the same time, so the main control unit 15 stores a value of 400 kilobytes in the storage unit 14.

Since the driving conditions of the magnetic tape recording device have been satisfied (step A5, Yes), the second timer 13 is started (step A7), and the magnetic tape recording device 120 is started.
Drive. If the magnetic tape recording apparatus has completely started up (step A8, Yes), the second timer 1
3 is read. Assuming that the value of the second timer 13 is 120 milliseconds, this value is notified to the storage unit 14 (step A9). Next, from the buffer 11 to the magnetic tape recording device 1
Data transfer is started to step 20 (step A10).
When the buffer 11 becomes empty (Step A12, Yes), the main control unit 15 stops the magnetic tape recording device 120 (Step A13), and when there is a command in the main control unit 15 (Step A15, Yes), the main control unit 15 again operates. It returns to step A1.

Third Specific Example As shown in FIG. 6, this specific example is also a case where the buffer 11 is expected to be full soon. The difference from the second specific example is that The fine adjustment of the driving conditions was performed using the actual measured values.

Since there is a command in the main control unit 15, data transfer is performed from the host device 100 to the buffer 11 (step A1). Since the value "400 kilobytes, 120 milliseconds" is stored in the storage unit 14 as described in the second specific example, the rise time of the magnetic tape recording device is one.
Although it was predicted to be 00 milliseconds, the drive conditions of the magnetic tape recording device are changed using this value.

That is, {5 (kilobytes)} T (milliseconds) × 120 (milliseconds) + b (kilobytes) <50
0 ° (step A5). When 380 kilobytes of data are stored in the buffer 11 (b = 380), similarly, if the first timer 12 reads a value of 5 milliseconds, {5 (kilobytes)} 5 (milliseconds) × 120
(Milliseconds) + 380 (kilobytes) = 500 ≥ 50
0｝, and it is predicted that the buffer 11 will be full after 120 milliseconds (predicted line in FIG. 6), so that the magnetic tape recording device driving condition is satisfied.

Thereafter, if the data transfer state is the same, the drive condition of the magnetic tape recording device is changed by setting the value of the storage unit 14 to the time required for the magnetic tape recording device 120 to start up. The driving conditions of the magnetic tape recording device described here use only the value of the rise time of the magnetic tape recording device 120 of the timer, and are merely examples. For example, a driving condition of the magnetic tape recording apparatus such as using an average value of the value of the second timer 13 and the value of the timer of the storage unit 14 can be cited as an example.

[II] Second Embodiment In the present embodiment, the buffer 11 is
When the buffer 11 is full when data is transferred to 0, the data transfer from the host device 100 to the buffer 11 is stopped and the storage unit 14 stores the fact that the buffer is full. different.

The overall operation of the present embodiment will be described in detail with reference to the flowcharts of FIGS. Note that in FIG. 7, steps B1 to B7 are the same operations as steps A1 to A7 in FIG.

Assume that the magnetic tape recording device 120 starts up (step B8 in FIG. 7), reads the value of the second timer 13, and notifies the storage unit 14 of the value of the second timer 13 (step B9). Here, it is assumed that after the data transfer from the buffer 11 to the magnetic tape recording device 120 is started, the buffer becomes full (step B11, Yes).
At this time, the data transfer from the host device 100 to the buffer 11 is stopped (step B14), and the fact that the buffer is full is stored in the storage unit 14. Thereafter, the same operation is performed, and the process returns to step B1 to determine the drive condition of the magnetic tape recording device (step B5).

At this time, the storage unit 14 stores the value of the second timer 13 and the fact that the buffer is full. The fact that the buffer is full indicates that the rise time of the magnetic tape recording device is shorter than expected, so that the magnetic tape recording device drive condition is determined to be shorter than the current judgment condition. By driving the tape recording apparatus, it is predicted that the buffer 11 can be prevented from being full, and the suspension of data transfer from the host apparatus 100 to the buffer 11 can be prevented. For this reason, data transfer efficiency can be improved.

[0038]

As described above, according to the present invention, the fine data is stored on the basis of the driving conditions of the magnetic tape recording device including the amount of data stored in the buffer and the rise time until the magnetic tape recording device reaches a steady speed. Since the data transfer control is performed while performing the adjustment, the data transfer from the host device to the magnetic tape recording device via the buffer can be performed while always maintaining the high-speed transfer.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of first and second embodiments of the present invention.

FIG. 2 is a schematic flowchart of the first embodiment.

FIG. 3 is a flowchart of the first embodiment.

FIG. 4 is a prediction line in a case where there is a margin until the buffer becomes full.

FIG. 5 is a prediction line in a case where there is no remaining capacity until the buffer becomes full.

FIG. 6 is a prediction line in the case where there is no remaining capacity until the buffer is full, but is a prediction line in the case where fine adjustment of the driving condition is performed using the actual measurement value executed in FIG. 5;

FIG. 7 is a flowchart of the second embodiment.

FIG. 8 is a system configuration diagram of a conventional example.

FIG. 9 is a flowchart of a conventional example.

[Explanation of symbols]

 Reference Signs List 10 magnetic tape control device 11 buffer 12 first timer 13 second timer 14 storage unit 15 main control unit 100 host device 120 magnetic tape recording device

Claims (5)

[Claims] 1. A buffer control method in a data transfer control device for writing data held by a higher-level device to a magnetic tape recording device via a buffer provided in the data transfer control device, wherein the data storage amount of the buffer and the magnetic tape A buffer control method in a data transfer control device, wherein the data transfer control is performed based on driving conditions of a magnetic tape recording device including a rise time until the recording device reaches a steady speed. 2. A transfer control is performed by measuring a time required for the magnetic tape recording device to reach a steady speed, and feeding back the measured time to a driving condition of the magnetic tape recording device. A buffer control method in the data transfer control device described in the above. 3. A buffer control method in a data transfer control device for writing data held by a host device to a magnetic tape recording device via a buffer provided in the data transfer control device, wherein the amount of data stored in the buffer is monitored. A first monitoring means, and a main control means for controlling the transfer of the predetermined amount of data from the buffer to the magnetic tape recording device when the data amount of the monitoring result of the first monitoring means is a predetermined amount. A buffer control method in a data transfer control device, comprising: 4. A second monitoring means for monitoring whether or not the magnetic tape recording device has reached a steady state, wherein the main control means determines that the monitoring result of the second monitoring means has reached a steady state. 4. The buffer control method in the data transfer control device according to claim 3, wherein when the determination is made, the transfer of the data stored in the buffer from the buffer to the magnetic tape recording device is started. 5. A buffer control method in a data transfer control device according to claim 1, wherein said magnetic tape recording device is an external storage device of a computer.