JP2595878B2 - Magnetic tape controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape control device which controls writing and reading of data to and from a magnetic tape as a recording medium in response to a request from a host device.

[0002]

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

Further, a magnetic tape device can overwrite (overwrite) recorded data. In a conventional magnetic tape device, when new data is additionally written on a recorded tape, the data is written in a forward direction. When reproduction is performed and a free space is generated in the read buffer, the block at this time is determined to be an old data block following the end of new data, and this data block is reproduced and this is an abnormal data block. Then, reproduction is performed in the reverse direction, a gap between blocks is detected, and additional writing of data is performed using that position as a start position of additional writing. Further, as one of measures to increase the speed and density and to improve 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 new data is additionally written to the recorded data, after the new data block is reproduced, the data is written in the reverse direction. When playing back,
As shown by an arrow C in FIG. 7A, if a data defect due to dust on the tape is present in the reproduced old data block, this is erroneously recognized as an inter-block gap, and the position shown by the arrow C is set as an additional writing start position. Additional writing of data is performed. Therefore, as shown in FIG. 5B, old remaining data that is not overwritten between the recorded new data block “n” and the additionally written data block “n + 1”. There is a problem that remains.

[0005] In addition, since a data defect is erroneously recognized as an inter-block gap, there has been a problem that a deviation occurs in management data for managing a block identification number.

The present invention has been made in order to solve such a problem. When new data is additionally written on a tape which has been recorded by overwriting, a data defect is included 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 without leaving old erased data even if there is an error, and without causing a shift in management data for managing block identification numbers.

[0007]

Means for Solving the Problems] The present invention magnetic tape control unit engagement Ru, the write data transferred from the host apparatus
The write buffer to be stored and the data sent from the magnetic tape unit
A read buffer for storing read data to be read,
The write buffer and the read buffer according to the instruction of the host device.
Main control unit that controls the operation of the buffer and the magnetic tape unit
And data of the magnetic tape as a recording medium.
For magnetic tape controller that controls writing and reading
The main control unit transmits the data from the magnetic tape device.
Of the read data based on the read data
Confirm the block identification number on the magnetic tape
Means for recognizing unit blocks of recorded data, adjacent
Between blocks of data blocks
Means to overwrite recorded tape by overwriting
Addition by reverse playback when additional data is written
When determining the write start position, the gap between the blocks
Recognize the detection result of the means for detecting
Based on the confirmation result of the block identification number
Inter-block gap after the first normal data block
Means for stopping the magnetic tape at the location of flops that, with a
It is characterized by.

Furthermore, in order to confirm the position of the magnetic tape by the block identification number of the data block, the unit Bed
The means to recognize the lock is recorded by overwriting
When writing new data to the data of
At the time of reproduction, the means for detecting the gap between the blocks,
Each time a gap is detected, a block in the read data
Block identification number that holds the block identification number in the internal register
And the block identification number stored in this internal register.
If it is confirmed that the number follows the
Update the block identification number stored in the data to the following number
In the case of reproduction in the reverse direction, the gap between the blocks is detected.
The reading data each time a gap is detected.
Block that holds the block identification number in the
Check with the block identification number and store in this internal register.
If you can confirm that it is the same as the lock identification number
Between the blocks after the first normal data block
It is characterized in that it is recognized as a gap.

[0009]

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 according to the present invention. In the figure, reference numeral 1 denotes a magnetic tape control device, 2 denotes an upper device, 3 denotes a magnetic tape device, and 11 denotes a transfer from the upper 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 read buffer 13 for the write buffer 11, the read buffer 12 and the magnetic tape device 3 in accordance with a command from the host device 2. A main control unit for controlling the operation, a write modulation circuit 14 for modulating the write data transferred from the host device 2 into a write format on the magnetic tape, and a reference numeral 15 for the read data sent from the magnetic tape device 3 The read demodulation circuit 16 demodulates the data into a format. An error correction circuit to be sent to the read buffer 12 to correct an error in the data subjected to I check. Note that the main control unit 13 is configured 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 host device 2 is input to the write buffer 11, further modulated by the write modulation circuit 14 into a write format on a 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 subjected to error correction by the error correction circuit 16, and then input to the read buffer 12. Host device 2
Transferred to

At this time, the read data output from the read demodulation circuit 15 is sent to the main control unit 13 at the same time. Then, the main control unit 13 checks whether or not the read data is a unit block, determines whether or not the read data is a normal data block, and detects whether or not there is a gap. These various operations are performed by an instruction (command) from the host device 2.

2 and 3 are flowcharts 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 control unit 13 determines whether or not a command has been input from the host device 2 (step 100). 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).

In step 101, if the command is a write command, 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). In the case of an additional write command in step 104, the main control unit 13 performs a control operation as described with reference to FIG.

FIG. 4 is a diagram showing a case in which n data blocks are overwritten (overwritten) on a recorded magnetic tape and the (n + 1) th and subsequent data blocks are additionally written. . If the command is additional writing, the main control unit 13 performs forward reproduction (step 106), and reads each data block.
The obtained block identification number is stored in the internal register.
To check if it is the number following the current block identification number
Thus, it is determined whether or not the data block is normal (step 107). If the data block is normal, an end signal is set (step 115), and the block identification number stored in the internal register is set. Perform an update. 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 inter-block gap (step 108).

In the case of the example shown in FIG.
Go to the position and stop. Playback is performed in the reverse direction from this position (step 109). When a gap is detected (step 110), the block stored in the internal register is read.
Whether the same block identification number as the identification number has been read
It is checked whether the data block is normal or not (step 111). If the data block is abnormal, the reproduction is continued. If the data block is normal, an end signal is set (step 112) and the internal register is set.
The block identification number to be kept is
Update the identification number and stop the tape (step 11
3).

In this manner, when detecting a gap,
Since the block identification number is collated each time, 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 erroneously recognized as an inter-block gap as shown in FIG. The tape position management data does not shift due to the presence of a data defect.

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 stops. Next, one block is reproduced from this position in the forward direction (step 114), the tape is stopped at the position indicated by the arrow A, and the block recognition held in the internal register is performed.
After updating the number, additional writing is started from this position (step 115). As a result, in the case of the example shown in FIG. 4, the (n + 1) th data is overwritten just above the old data block 1, so that the old unerased data as shown in FIG. Thus, the management data of the tape position does not shift.

[0018]

As described above, according to the magnetic tape controller of the present invention, when new data is additionally written on a tape already recorded by overwriting, a data defect exists in an old data block following the end of the new data. Even
There is an effect that old unremaining data does not remain unlike the related art, and a shift in management data for managing a tape position can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating 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 according to the embodiment of the present invention.

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 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)

(57) [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 the read buffer in response to a command from the host device. And a main control unit for controlling the operation of the magnetic tape device, wherein the main control unit controls writing and reading of data to and from a magnetic tape as a recording medium. The block identification number in the read data is confirmed based on the read data transmitted .
Means for recognizing a unit block of data recorded on a magnetic tape by Rukoto, means for detecting interblock gap between adjacent data blocks each other, the case of writing adding new data to a recorded tape by overwriting When determining an additional writing start position by reproduction in the reverse direction, the gap between blocks is detected.
The detection result of the means and the means for recognizing the unit block.
Means for stopping the magnetic tape at the position of the inter-block gap after the first normal data block based on the confirmed result of the confirmed block identification number . 2. The method according to claim 1,The means for recognizing unit blocks isOh
-Add new data to the recorded data
When writing in addition, when playing in the forward directionDetecting the gap between the blocks
The meansEach time a gap is detectedThe read data
Block identification number in the internal register
Check the block identification number and check the block stored in this internal register.
If it can be confirmed that it is the number following the
Follow the block identification number held in the internal register
Update to the number,  When playing in the reverse directionDetecting the gap between the blocks
Each time the means detects a gap,
Block that holds the block identification number of the
Checks the block number held in this internal register by comparing with the identification number.
When it is confirmed that the number is the same as the identification number
The gap between blocks after the first normal data block
Recognize that2. The method according to claim 1, wherein
The magnetic tape control device according to claim 1.