JPH0244579A - Data control system for magnetic tape control device - Google Patents

Abstract

PURPOSE:To attain exact reading only for a data block group to be needed by recording the discriminating number and writing ending position of the written data block group to the specified area of a magnetic tape and controlling the reading on the basis of this recording. CONSTITUTION:A processor 5 of a magnetic tape control device 3 reads the final position of the preceding data block group, which is recorded to the specified area of a magnetic tape 1, in correspondence to the program of an indicating means 11 and moves the tape 1 to the position. The data block group, which is supplied from a high order device 2, temporarily stored in a RAM 7 and error-corrected by a data transfer control circuit 9, is written to the tape 1. Next, the tape 1 is rewound in the specified area and retrieving information, which are housed to the RAM 7 together with the data clock group, from the device 2, the recording order number and data ending position of the data block group are written to the specified area. Then, the reading is controlled on the basis of these information and the data block group to be needed is exactly sent to the device 2. Then, the processing efficiency of the high order device side is prevented from being lowered by unnecessary data.

Description

[Detailed Description of the Invention] [1 Already Required] This invention relates to a data management method for a magnetic tape control device that reliably detects the end position of valid data written on a magnetic tape and prevents reading of invalid data. In a magnetic tape control device that controls a magnetic tape device to read and write data blocks to and from the magnetic tape, the purpose is to read up to valid data blocks and not read invalid data blocks. When writing a data block group, an instruction is given to record the write end position of the last data block written in the data block group, and index information for each data block group sent by the host device is recorded on the magnetic tape. An instruction means is provided for instructing to convert and distinguish in the order in which data is written, and based on instructions from the instruction means, a specific area provided at the starting end of the magnetic tape adjacent to the first data block to be written on the magnetic tape is provided.
In the order of writing, starting from the first written data block group,
The number that distinguishes data block groups and the writing end position of the last data block written for each data block group are recorded, and when reading the data block group specified by the host device, it is necessary to write to a specific area. The number of the recorded data block group and the write end position are read, and when the data blocks up to the write end position of the data block group are read, the read operation is ended.

[Industrial application field]

The present invention relates to a magnetic tape control device, and more particularly to a data management system for a magnetic tape control device that reliably detects the end position of valid data written on a magnetic tape and prevents invalid data from being read.

When the processing of data recorded on the magnetic tape is completed, new data is written while erasing this data from the beginning of the magnetic tape.

Therefore, when writing of new data is completed, old invalid data may remain on the magnetic tape after the writing end position.

Therefore, an EOD (End of Data) mark indicating the end position of new data is recorded on the magnetic tape, but if this EOD mark is detected incorrectly, invalid data will be read. It is necessary that the end position of new data can be clearly detected.

[Conventional technology]

FIG. 5 is a diagram explaining the conventional technique.

Newly written data blocks are sequentially recorded on the magnetic tape 1, and when the final data block ■ is recorded,
An EOD mark (■) is recorded after this data block (■). If old data is recorded on magnetic tape 1 and this old data is left without being erased, the EO
After the D mark, the invalid data block ■ remains recorded.

[Problem to be solved by the invention]

The magnetic tape controller receives data from an upper level device such as a channel.
When instructed to read data blocks up to OD,
When the magnetic tape device is instructed to read a data block and the magnetic tape device reads the EOD mark shown in FIG. The magnetic tape control device may have detected a defect in the F, OD area, etc.
If it is not possible to recognize that the mark ■ has been read, the invalid data block ■ recorded following the EOD mark ■ is read out.

Therefore, if the invalid data block ■ is not normal, an error will be detected in the magnetic tape control device and reported to the host device, but if the invalid data block ■ is normal, unnecessary data processing will be carried out by the host device. In either case, there is a problem in that the processing efficiency on the host device side is reduced.

In view of these problems, the present invention provides an area at the leading end of the magnetic tape to record the effective writing end position of the data block, and when reading the data block, the data block written in this area is recorded. The purpose of this invention is to read the end position, recognize the end position, and then read the data block to ensure that valid data blocks are read and invalid data blocks are not read.

[Means to solve the problem]

FIG. 1 is a block diagram of the principle of the present invention, and FIG. 2 is a diagram illustrating an example of the format of the magnetic tape of the present invention.

The magnetic tape control device 3 connects the magnetic tape device 4 to an interface circuit 10 and connects the host device 2 to an ink face circuit 8. The processor 5 of the magnetic tape control device 3 reads and operates the program stored in the control memory 6, and communicates with the interface circuit 8 in order to perform data transfer between the host device 2 and the magnetic tape device 4. 10 and data transfer control circuit 9.

The processor 12 of the magnetic tape device 4 reads and operates the program stored in the ROM 13, and processes the program via the interface circuit 14 to the processor 5 of the magnetic tape control device 3.
It analyzes the command sent by the controller 1 and controls a motor drive circuit (not shown) to control the running of the magnetic tape 1.

As shown in FIG. 2, a specific area 19 is preset on the magnetic tape 1.
is set, for example, between the data blocks (2) written first in the ARA area area amount.

In this specific area 19, for example, a code indicating that it is a specific area, a number indicating the recording order of valid data block groups, and the number of data blocks indicating the writing end position for each data block group are recorded. Ru.

When the processor 5 is instructed to write a data block from the host device 2, it reads out the instruction means 11 and instructs the processor 12 to run the magnetic tape 1 shown in FIG. When the magnetic head 17 at the position of BOT ■ indicating the start end is placed in the ARA area, the ARA area area is read out and the gain of the automatic gain adjustment amplifier circuit of the data transfer control circuit 9 is adjusted. let

Then, when the magnetic heel 17 is next positioned in the specific area 19, a code indicating that it is the specific area is read out. When the processor 5 recognizes the specific area 19, it checks whether there is any recording in this specific area 19, and if there is no recording, it waits for the magnetic head 17 to pass through this specific area 19.

Then, the interface circuit 8 and the data transfer control circuit 9
The data block to be transferred by the host device through
0 and 14 to the write circuit 15, and the magnetic head 1
7, data blocks are sequentially written onto the magnetic tape 1 from the position of the data block (2) shown in FIG.

The processor 5 records in the RAM 7 the index information of the valid data block group transferred by the host device 2, the number indicating the recording order in which this data block group was recorded, and the data block number indicating the writing end position of this data block group. When the writing of the data block group transferred from the host device is completed, it instructs the processor 12 to write the data blocks on the magnetic tape 1.
When the magnetic head 17 detects BOT■, the magnetic tape 1 is run in the forward direction again, and the magnetic head 1
7 is positioned in the specific area 19.

Then, the processor 5 sends the number indicating the recording order of the valid data block group recorded in the RAM 7 and the number of data blocks indicating the write end position to the write circuit 15 via the data transfer control circuit 9 and interface circuits 10 and 14. The data is sent out and written in this specific area 19 via the magnetic head 17.

When the processor 5 is instructed to write the next data block group, it reads the specific area 19 and reads the number indicating the recording order of the data block group and the number of data blocks.
The magnetic tape 1 is run to the write end position of the last data block of the last data block group that has already been recorded, based on the number of the data block group that has already been written and the data block number that indicates the write end position. After
Subsequently, the next data block group is written on the magnetic tape 1.

When the processor 5 is instructed to read the data block group by specifying the index information of the data block group from the host device 2, the processor 5 performs magnetic recording on the specific area 19 of the magnetic tape 1 in the same manner as described above based on the instruction from the instruction means 11. Position the head 17, read the data block number indicating the recording end position of the specified data block group from the index information recorded in the RAM 7 and the number of the data block group, and read the data block number indicating the recording end position of the specified data block group. After positioning the magnetic head 17, the data transfer control circuit 9 sequentially reads out the data blocks via the readout circuit 16 and ink face circuits 14 and 10, and performs demodulation, error detection and correction, etc., and then the interface circuit 8. When the data blocks corresponding to the number of data blocks read from the specific area 19 are transferred to the host device 2, the read operation is ended.

[Effect]

With the above configuration, the processor 5, based on the instruction from the instruction means 11, assigns a number to distinguish a new data block group to be written to the specific area 19 set on the magnetic tape 1, and a number to write the data block group. In order to record the end position, when reading this data block group, by reading in advance the number of the data block group recorded in the specific area 19 and the writing end position of the last written data block, It becomes possible to sell only the precisely required data block group.

Therefore, it is possible to prevent the processing efficiency of the host device 2 from being reduced by reading invalid data blocks left on the magnetic tape 1 and causing an error, or by sending invalid data blocks to the host device 2. I can do it.

〔Example〕

FIG. 3 is a block diagram of a circuit showing one embodiment of the present invention.
FIG. 4 is a flowchart illustrating the operation of FIG. 3.

The same reference numerals as in FIG. 1 indicate the same functions. The processor 5 of the magnetic tape control device 3 receives a write command from the host device 2 via the interface circuit 8 and data transfer control circuit 9 in accordance with instructions from the instruction program 18 stored in the control memory 6 as shown in FIG. We are monitoring whether
If the input command is a write command, the command is sent to the processor 12 via the data transfer control circuit 9, interface circuit 10, and interface circuit 14 of the magnetic tape device 4 to direct the magnetic head 17 to the specific area 19 shown in FIG. Give instructions for positioning.

The processor 12 operates by reading a program from the ROM 13 and controls a motor drive circuit (not shown) to run the magnetic tape 1 and position the magnetic head 17 in a specific area 19. Therefore, the data read by the magnetic head 17 is transmitted to the interface circuit 14 and I via the read circuit 16.
The data is sent to the processor 5 via the data transfer control circuit 9 via the data transfer control circuit 9.

The processor 5 checks whether there is a record in the specific area 19 as shown in FIG. The input data blocks are sequentially written from the storage area of the data block following the specific area 19 of the magnetic tape 1 as explained in FIG. 1, and the number of transferred data blocks is counted and recorded in the RAM 7 .

When writing of the data block group is completed, the processor 5
As shown in FIG. 4, when the magnetic tape 1 is rewound and the magnetic nozzle 17 is positioned in the specific area 19, the index information for indexing the group of data processors 7 transferred by the host device 2 is transferred to the magnetic tape 1. It is converted into a number determined by the order in which it was recorded on tape l, and this index information and number are stored in RAM as a table.
7, this number and the number of data blocks indicating the writing end position where the last data block of this data block group was written, that is, the number of transferred data blocks, are read out from the RAM 7 and shown in FIG. The data is written in a specific area 19 as shown.

Then, as shown in FIG. 4 again, the process returns to the routine for monitoring the human power of the write command. When instructed to write the next data block group, the processor 5 checks whether there is any recording in the specific area 19 as shown in FIG.

In this case, since the data block group has already been written, there is a record in the specific area 19. Therefore, from the data block group number and the data block number indicating the write end position, the processor 5 moves the magnetic tape to the write end position of the last data block of the data block group that has already been written, as shown in FIG. 1 is run and data blocks are written following this last data block. Then, as shown in FIG. 4, the magnetic tape 1 is rewound, and the number and the number of data blocks are written in the specific area 19 as before, and then the routine returns to monitoring the input of a write command.

As shown in FIG. 4, when the input instruction is not a write instruction, the processor 5 checks whether it is a read instruction. If it is not a read command, the process moves to another process based on the input command, and if it is a read command, the magnetic head 17 is positioned in the specific area 19 of the magnetic tape 1 in the same manner as described above.

Then, the index information of the data block group sent by the host device 2 is converted into a corresponding number by referring to a table stored in the RAM 7.

As shown in FIG. 4, the processor 5 calculates, from the converted number,
Recognizes the writing end position of the data block group with the number one before the converted number in the specific area 19, and writes the data block on the magnetic tape 1.
is moved to position the magnetic head 17 at the first data block of the data block group designated by the host device 2.

Then, as shown in FIG. 4, the data block is read out,
Based on the converted number, it is checked whether the specified number of data blocks of the corresponding data block group read from the specific area 19 have been read.

That is, check whether the specified number of data blocks have been read,
If the specified number of data blocks has not yet been reached, the data block is read, and when the specified number of data blocks has been reached, the read operation is terminated, and as shown in FIG. 4, the routine monitors the input of a write command. Return to

〔Effect of the invention〕

As explained above, the present invention makes it possible to accurately read only the required data block group, so it is possible to read out invalid data blocks left on the magnetic tape, thereby preventing errors from occurring or invalid data blocks being read out. By sending the information to the higher-level device, it is possible to prevent the processing efficiency of the higher-level device from decreasing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention. FIG. 2 is a diagram illustrating an example of the formant of the magnetic tape of the present invention. FIG. 3 is a block diagram of a circuit showing an embodiment of the present invention. is a flowchart explaining the operation of FIG.
The figure is a diagram explaining a conventional technique. In the figure, 1 is a magnetic tape, 2 is a host device, 3 is a magnetic tape system +B device, 4 is a magnetic tape device, 5 and 12 are processors, 6 is control memory, 7 is RAM, 8 and 10.14 are interfaces. circuit, 9 is a data transfer control circuit, 11 is an instruction means, 13 is a ROM, 15 is a write circuit, 16 is a read circuit, 17 is a magnetic head, 1
8 is the instruction program, the format for the Sekibonran theme in August of this year... Y 4
figure

Claims (1)

[Claims] In a magnetic tape control device (3) that controls a magnetic tape device (4) to write and read data blocks to and from a magnetic tape (1), new data is added to the magnetic tape (1). When writing a block group, an instruction is given to record the writing end position of the last written data block in the data block group, and
An instruction means (11) is provided for instructing to convert and distinguish index information for each data block group sent by the host device (2) in the order recorded on the magnetic tape (1), and the magnetic tape (1) Based on the instruction from the instruction means (11), data blocks are sequentially written starting from the data block group written first in a specific area provided on the starting end side of the magnetic tape (1) adjacent to the first data block written on the magnetic tape (1). Record the number that distinguishes the data block group and the write end position of the last written data block for each data block group in the writing order, and then read the data block group specified by the host device (2). When the data block group is read out, the number and write end position of the corresponding data block group recorded in the specific area are read, and when the data blocks up to the write end position of the data block group are read, the read operation is ended. A data management method for magnetic tape controllers.