JPH07110907A - Magnetic tape controller - Google Patents

Abstract

PURPOSE:To made possible accurate positioning regardless of any data defect existing within an old data block in the writing of new data additionally onto a tape already recorded by overwriting by imparting functions of recognizing a data unit block, detecting a gap between data blocks and the like to a main control section. CONSTITUTION:A writing data being transferred from a high-order device 2 during writing are stored into a writing buffer 11 and further modulated in a writing format on a magnetic tape with a writing modulation circuit 14 to be inputted into a magnetic tape device 3. On the other hand, reading data being fed from the magnetic tape device 3 during reading is demodulated with a read demodulation circuit 15, inputted into a read buffer 12 after error correction is made with an error correction circuit 16 and transferred to the high-order device 2. At this point, a main control section 13 checks to see whether the reading data to be outputted from the read demodulation circuit 15 is a normal unit block or not while detecting the presence of a gap.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape controller for controlling writing and reading of data on a magnetic tape which is a recording medium in response to a request from a host device.

[0002]

2. Description of the Related Art Generally, on a magnetic tape, which is a recording medium of a magnetic tape device, data is written into each block, which is a physical unit of data, which is read and written by one operation, and between blocks. , An empty block gap of about 1/2 inch (inter bl
ock gap) is provided.

Further, the magnetic tape device is capable of overwriting (overwriting) the recorded data, and in the conventional magnetic tape device, when new data is additionally written on the recorded tape, it is forwarded. When reproduction is performed and a free space is generated in the read buffer, it is determined that the block at this time is an old data block following the end of new data, this data block is reproduced, and this is an abnormal data block. After confirming that, the reproduction is performed in the reverse direction, the inter-block gap is detected, and the additional writing of data is performed using the position as the start position of the additional writing. Further, as one of measures for increasing the speed and increasing the density and improving the reliability and operability, a method of confirming the position of the magnetic tape by a sequential block identification number of the data block is adopted.

[0004]

Since the conventional magnetic tape control device operates as described above, when additionally writing new data to the recorded data, after the new data block is reproduced, the reverse direction is reversed. When performing playback,
As indicated by arrow C in (a), if a data defect due to dust on the tape exists in the reproduced old data block, this is erroneously recognized as an inter-block gap, and the position indicated by arrow C is set as the additional write start position. Additional writing of data is performed. Therefore, as shown in FIG. 5B, old unerased data that is not overwritten between the new recorded data block “n” and the additionally written data block “n + 1”. There is a problem that remains.

Further, since the data defect is erroneously recognized as the inter-block gap, there is a problem that the management data for managing the block identification number is displaced.

The present invention has been made to solve the above problems, and when new data is additionally written to a recorded tape by overwriting, a data defect is generated in an old data block following the end of the new data. It is an object of the present invention to provide a magnetic tape control device capable of performing control such that old unerased data does not remain even if there is an error, and the management data for managing the block identification number is not displaced.

[0007]

In the magnetic tape controller according to the present invention, the main controller recognizes the unit block of the data recorded on the magnetic tape based on the read data sent from the magnetic tape device. And a means for detecting the inter-block gap between adjacent data blocks, and the first normal operation when determining the additional write start position by playing in the opposite direction when new data is additionally written on the recorded tape by overwriting. And a means for stopping the magnetic tape at the position of the inter-block gap after a certain data block.

Further, in order to confirm the position of the magnetic tape by the block identification number of the data block, means for updating the block identification number of the data block each time a gap between blocks between adjacent data blocks is detected,
When writing new data to the recorded data by overwriting, the block identification number is updated by detecting the gap between blocks after a normal data block when playing in the forward direction, and first when playing in the backward direction. And means for updating the block identification number by detecting the gap between blocks after the normal data block.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the basic configuration of a magnetic tape control device of the present invention. In the figure, 1 is a magnetic tape control device, 2 is a higher-level device, 3 is a magnetic tape device, and 11 is transferred from the higher-level device 2. A write buffer for storing write data, a read buffer 12 for storing data sent from the magnetic tape device 3 at the time of reading, and a reference numeral 13 for the write buffer 11, the read buffer 12 and the magnetic tape device 3 in response to an instruction from the host device 2. A main control unit that controls the operation, 14 is a write modulation circuit that modulates the write data transferred from the higher-level device 2 into a write format on the magnetic tape, and 15 is an original read data sent from the magnetic tape device 3. A read demodulation circuit for demodulating into a format, 16 is a parser of read data output from the read demodulation circuit An error correction circuit to be sent to the read buffer 12 to correct an error in the data subjected to I check. The main control unit 13 is configured by using a microcomputer.

First, the basic operation of the magnetic tape device will be described, and then the operation of the embodiment of the present invention will be described. At the time of writing, write data transferred from the higher-level device 2 is input to the write buffer 11, further modulated by the write modulation circuit 14 into a write format on the magnetic tape, and then input to the magnetic tape device 3. On the other hand, at the time of reading, the read data sent from the magnetic tape device 3 is demodulated by the read demodulation circuit 15, further error-corrected by the error correction circuit 16, and then input to the read buffer 12 and then read from the read buffer 12. Host device 2
Transferred to.

At this time, the read data output from the read demodulation circuit 15 is simultaneously sent to the main control unit 13. Then, the main control unit 13 confirms whether or not the read data is a unit block, determines whether or not the read data is a normal data block, and detects the presence or absence of a gap. These various operations are performed by commands from the higher-level device 2.

2 and 3 are flow charts showing the operation of the embodiment of the present invention, and FIG. 4 is a diagram for explaining the control operation of the embodiment of the present invention. First, the main controller 13 determines whether or not a command has been input from the higher-level device 2 (step 100). Then, when a command is input, it is determined whether the command is a write command or a read command (step 101). And
If the command is a read command, the command is executed (step 102) and the read buffer 12
This command is executed until is full (103).

If the command is a write command in step 101, the main control unit 13 determines whether the command is an additional write (10).
4). If the command is not a command for additional writing, the command (normal writing) is executed (step 105). Further, in the case of the additional write command in step 104, the main controller 13 performs the control operation as described in FIG.

FIG. 4 is a diagram showing a case where n data blocks are overwritten (overwritten) on a recorded magnetic tape, and the n + 1th and subsequent data blocks are additionally written after that. . If the command is additional writing, the main control unit 13 performs reproduction in the forward direction (step 106), determines whether or not the data block is normal (step 107), and sets an end signal if normal (step 106). Step 115), the block identification number is updated. Then, reproduction in the forward direction is continued until an abnormal data block is detected. When an abnormal data block is detected, the tape is stopped at the position of the interblock gap (step 108).

In the case of the example shown in FIG. 4, the tape is an arrow B.
Go to the position and stop. When reproduction is performed in the reverse direction from this position (step 109) and a gap is detected (step 110), it is confirmed whether or not the data block is normal (step 111). When the data block is abnormal, the reproduction is further continued, but when the data block is normal, an end signal is set (step 112), the block identification number is updated, and the tape is stopped (step 11).
3).

As shown in FIG. 4, even if a data defect indicated by an arrow C exists in an old data block following the end of new data, this data defect is not mistaken as an inter-block gap and does not operate. Further, the management data of the tape position will not be displaced due to the existence of the data defect.

Then, in the case of the example shown in FIG. 4, the reproduction in the reverse direction proceeds to the position of the inter-block gap indicated by the arrow D and the tape is stopped. Next, one block is reproduced in the forward direction from this position (step 114), the tape is stopped at the position indicated by arrow A, and additional writing is started from this position (step 115). As a result, in the case of the example shown in FIG.
The n + 1th data is overwritten directly on the old data block 1, the old unerased data as shown in FIG. 5B does not remain, and the management data of the tape position does not shift. .

[0018]

As described above, in the magnetic tape control device of the present invention, when new data is additionally written to the recorded tape by overwriting, a data defect exists in the old data block following the end of the new data. Even if
There is an effect that old unerased data does not remain as in the conventional case, and deviation of the management data for managing the tape position can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a magnetic tape control device.

FIG. 2 is a flowchart showing the operation of the embodiment of the present invention.

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

FIG. 4 is a diagram for explaining a control operation of the embodiment of the present invention.

FIG. 5 is a diagram for explaining a problem of the conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 magnetic tape control device 2 host device 3 magnetic tape device 11 write buffer 12 read buffer 13 main control unit 14 write modulation circuit 15 read demodulation circuit 16 error correction circuit

Claims (2)

[Claims] 1. A write buffer for storing write data transferred from a host device, a read buffer for storing read data sent from a magnetic tape device, and the write buffer and read buffer in response to a command from the host device. And a main control unit that controls the operation of the magnetic tape device, and that controls writing and reading of data to and from a magnetic tape that is a recording medium. Means to recognize the unit block of the data recorded on the magnetic tape based on the read data sent, Means to detect the inter-block gap between adjacent data blocks, Overwrite new data on the recorded tape Determine the additional writing start position by playing in the reverse direction when additional writing is performed. A magnetic tape control device comprising means for stopping the magnetic tape at the position of the gap between blocks after the first normal data block. 2. A means for controlling the position of a magnetic tape by updating the data block identification number each time the main control unit detects an inter-block gap between adjacent data blocks, and using the sequential identification number of the data block. When writing new data to the recorded data by overwriting, the block identification number is updated by detecting the inter-block gap after the normal data block when playing in the forward direction, and when playing in the backward direction. 2. The magnetic tape controller according to claim 1, further comprising means for updating the block identification number by detecting an inter-block gap after the first normal data block.