JPH01304524A - Magnetic tape controller - Google Patents

Abstract

PURPOSE:To improve the reliability of a magnetic tape controller by checking whether or not the check byte number is normally left within the tape controller after data are transferred to a host device. CONSTITUTION:A magnetic tape controller 13 controls the transmission and reception of data between a host device 11 and a magnetic tape device 14 and consists of a host device connecting part 15, a data compressing part 12, a data buffer 16, a writing part 17, a reading part 18, a device connecting part 19, and a microprocessor 20. The write data is transferred to the controller 13 from the device 11 and compressed by the part 12 via the part 15. This compressed data is written into the buffer 16. When this writing job 17 is through, the compressed data is sent to the device 14 through the part 19 and then restored by the part 12 and sent to the device 11 in a data reading state. Then it is checked whether the added check bytes remain in the prescribed number or not for decision whether the data byte number to be transferred is correct or not.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic tape control device, and more particularly to a magnetic tape control device that is capable of detecting errors in the amount of data transferred to a host device! Regarding.

[Conventional technology]

With regard to data transfer between an external storage device such as a magnetic tape device and a host device, as the amount of data to be handled increases, various methods have been proposed with the aim of increasing the efficiency of storage capacity and shortening transfer time. For example, Tokuko Sho 61-24686
No. 5 includes a data selection means for selecting significant data to be transferred from a specific f'IIt information group, a selection instruction signal to the data selection means, and encoding representing the format of the selected significant data. By comprising a control circuit means for creating data format information and a means for switching and transmitting meaningful data and data format information, the transfer operation of invalid data is stopped and only meaningful data is transferred. something is known. In other words, data is compressed by encoding data to improve data transfer efficiency, but in order to detect errors in the amount of data transferred to a host device, for example, it is necessary to check the number of bytes to be transferred and the bytes actually transferred. Errors were detected by comparing numbers.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, when a function such as data compression is added to the data transfer path, it is not possible to compare the number of data bytes to be transferred to the host device and the number of bytes actually transferred. Moreover, when a data compression function or the like is added, there is a problem in that the provision does not take into account error detection in the number of transferred bytes, and it is not possible to detect hardware failures in the own device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic tape @J device that is capable of detecting hardware failures in its own device.

[Means to solve the problem]

The above purpose is to check the number of bytes on the magnetic tape after data transfer to the host device is completed in a magnetic tape control device that controls data transmission and reception between the host device and the magnetic tape device.
This is achieved by providing a circuit that detects whether the ff1l ml remains normally in the device.

[Effect]

The magnetic tape control device according to the present invention has a data compression function, and in order to determine whether the number of data bytes to be transferred to the host device is correct, a check byte added after the restored data is a predetermined number of bytes. The normality of the number of data bytes transferred from K is guaranteed by detecting whether the number of data bytes remains. From this K, I L (
IncorrectLength) errors, that is, data where the number of transferred bytes is greater than the number of requested data bytes, can be prevented, and hardware failures in the own device can be detected by the own device.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1st
In the figure, a magnetic tape control device is shown, which controls data transmission and reception between a host device 11 and a magnetic tape device 14 . This magnetic tape control device can be roughly divided into a host device connection section 15 which is an interface with the host device t11, a data compression section which compresses and restores data, a data buffer 16, and a data writing section to the magnetic tape device 14. of? ! a writing section 17 that controls the li'lI; a reading section 18 that controls data reading from the magnetic tape device 14;
, a device connection section 19 that interfaces with the magnetic tape device 14, and a microprocessor 20 that controls each section of the magnetic tape control device 15.

Write data is sent from the host device 11 to the magnetic tape control device 1
3, the data is compressed by the data compression unit 3 via the host device connection unit 15, and then written to the data buffer 16. After that, write N517, device connection part 1
9 are all passed through and sent to the magnetic tape unit [14]. On the other hand, when reading data from the magnetic tape device 14, the read data enters the data buffer 16 through the device connection section 19 and the reading section 18. This data is restored by the data compression section and transferred to the host device 11 via the host device connection section 15. At this time, the format of the data sent from the data buffer 16 to the data decompression unit 122 of the data compression unit (3) is shown as (A) in FIG. The formant of the data is shown as (B) in FIG. Second
As is clear from the figure, it is not possible to compare the number of data bytes before and after data restoration. The data format after restoration is composed of restoration data and check bytes, and only the restoration data is transferred to the host device 11, and the check bytes are not transferred.

In this embodiment, the check byte is 2 bytes. Therefore, the host device 11 determines whether the number of transferred bytes is correct or not.
After data transfer is completed, it is detected that the check byte is 2 bytes, and the normality of transferred byte a is confirmed. If the check byte is other than 2 bytes, it is reported as a transfer byte count error.

Next, FIG. 3 shows an example of a circuit for detecting that the check byte is 2 bytes. In this embodiment, this detection circuit is provided in the host device connection section 15 within the magnetic tape control device u. In FIG. 5, 1 and 2 are counters S1 and T, 5 is a comparator, 4 is an NkND gate, and 5 is a combinational circuit. Also, 5TROB-P
The signal is a signal that is output in synchronization with the restored data and the check byte, and the TRANSPULS-P signal is a signal that is output in synchronization with the data transferred from the higher-level device connection section 15 to the higher-level device 11. Forward read FORWA
RD-P), the combinational circuit 5 causes Kakunter T2.
After the data transfer is completed, the count values of Kakuntar S1 and Kakunta T2 are compared by comparator 3, and if they do not match, it is reported as an error.The data format after restoration is shown in Figure 4. Show.4th
In the figure, forward reading (FORWARD-P) is shown as an example, but backward reading (BACKWARD-P) is shown as an example.
Alternatively, if the number of check bytes differs in the 2-byte simultaneous transfer mode (6MBYTE-P), etc., the combinational circuit 5 changes the initial setting count value.

As explained above, according to this embodiment, it is possible to check the number of bytes transferred to the host device.

〔Effect of the invention〕

According to the present invention, even if the magnetic tape control device is provided with a data compression function such as encoding to cope with an increase in the amount of data, it is possible to detect whether the number of bytes of data transferred to the host device is normal or not. . Furthermore, detection of a hardware failure that is the cause of an abnormality in the number of data transfer bytes does not depend on the host device (it can be detected within the magnetic tape control device), thereby improving the reliability of the device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a magnetic tape control device according to the present invention, FIG. 2 is an explanatory diagram showing an example of a transfer data format in the magnetic tape control device, and FIG. 3 is a block diagram showing an example of a transfer data format in the magnetic tape control device. A circuit diagram showing one embodiment of the detection circuit, and FIG. 4 is a time chart explaining the operation of the circuit shown in FIG. 3. 1-#y Kunta 8.2...Kakunta T, 3...
Comparator, 4... NAND gate, 5... Combination circuit, 11... Host device, 12... Data compression unit, 15... Magnetic tape control device, 14... Magnetic tape device, 15... ... Upper device connection section, 16... Data buffer, 17... Loading section, 18... Reading section,
19...Device connection section, 20...Microprocessor, 21...Check byte.

Claims (1)

[Scope of Claims] 1. In a magnetic tape control device that includes data compression means such as encoding and controls data transmission and reception between a host device and a magnetic tape device, the magnetic tape A magnetic tape control device comprising: a detection means for detecting whether or not the amount of transferred data is a predetermined amount after data is transferred from the device to the host device. 2. The magnetic tape control device according to claim 1, wherein the detecting means comprises a circuit for checking the number of check bytes after data transfer is completed.