JPH0224875A - Recorder - Google Patents

Abstract

PURPOSE:To indicate a compression rate not only to a recorder, but also to a host device by providing a counting means which counts the number of bytes of data blocks sent from the host device, counting means which counts the number of bytes written in a compressed state, and controlling means which calculates the compression rate of data by using counting results of both counting means. CONSTITUTION:A counting means 8 counts the number of bytes at every data block sent from a host device 1 and another counting means 7 counts the number of bytes at every data block compressed by a data compression circuit 3. A controlling means 9 calculates the sum of the total number of bytes before compression and total number of bytes after compression written on one reel of magnetic tape and the total number of data blocks written on the tape from compression complete signals generated from the circuit 3. Thereafter, the means 9 calculates an average compression rate from the sum of the total numbers of bytes and total number of data blocks. Therefore, the means 9 can display the calculated average compression rate on a panel and at the same time, send the average compression rate to the host device 1 through a control circuit 2.

Description

[Detailed Description of the Invention] [Summary] Regarding a recording device that calculates the compression rate when compressed data is recorded on a recording medium, the present invention is capable of displaying the compression rate on the recording device and notifying the host computer of the compression rate. A control circuit that creates a pulse indicating 1-byte data transfer based on a response signal sent by the host device, compresses the data transferred by the control circuit, and generates a write pulse for each byte and a pulse for each data block. The recording device is equipped with a data compression circuit that generates a compression completion signal, and records data blocks compressed by the data compression circuit, and the data block transmitted by the host device is controlled by a pulse indicating data transfer transmitted by the control circuit. a first counting means for counting the number of bytes of a block; a second counting means for counting the number of bytes of a data block to be compressed and written to a recording medium using a write pulse created by the data compression circuit; and a data compression circuit. The compression completion signal sent by
The counting results of the first counting means and the second counting means are respectively tallied corresponding to the total number of data blocks written on the recording medium, and the counting results and the total number of data blocks written on the recording medium are added. and a control means for calculating the data compression ratio from the data compression ratio.

[Industrial application field]

The present invention relates to a recording device that calculates a data compression ratio when compressed data is recorded on a recording medium.

Some recent input/output devices compress and record data sent from a host computer. Magnetic tape devices are one of them, and in order to efficiently record data sent by a host computer onto magnetic tape,
Consideration has been given to compressing data and recording it on magnetic tape.

By the way, if the compression rate of the data compressed and written on the magnetic tape is unknown, the operator will not know how much data has been recorded, which is inconvenient when handling the magnetic tape, so the compression rate is not displayed. It is necessary to do so.

[Conventional technology]

For example, conventional magnetic tape devices record the data sent by the host computer as is, and the magnetic tape device does not compress this data before recording it, so of course it does not display the data compression rate. Also, no notification is made to the higher-level device.

[Problem to be solved by the invention]

However, when data sent by a host computer is compressed and recorded by a magnetic tape device, if the data compression rate is unknown, the operator cannot know how many data blocks have been recorded on the magnetic tape. Furthermore, there are various algorithms for compressing data, and the data compression rate varies depending on the data structure and the applied algorithm. Therefore, in order to know whether data can be efficiently recorded, it is necessary to display the compression ratio when data is actually recorded on a magnetic tape.

In view of these problems, an object of the present invention is to display the data compression rate on the magnetic tape device and notify the host computer of the data compression rate, for example, when a data block has been recorded on the magnetic tape. It is said that

[Means to solve the problem]

FIG. 1 is a block diagram of the principle of the present invention.

l is a higher-level device, for example, a channel. 2 is a control circuit for the magnetic tape device, which controls data transfer with the host device 1, requests data transfer from the host device 1, and transfers the data based on a response signal sent by the host device 1 along with 1 byte of data. Create a pulse indicating transfer.

3 is a data compression circuit which compresses the data sent out by the control circuit 2, sends the compressed data byte by byte to the data buffer memory 4, and sends a write pulse instructing writing of this data to the data buffer memory 4. Send to 4. Furthermore, a signal indicating that data compression for one data block has been completed is sent to the control means 9.

4 is a data buffer memory that stores compressed data. A write circuit 5 sends the data stored in the data buffer memory 4 to a write head 6 to write it on a magnetic tape (not shown).

7 is a second counting means that counts write pulses sent when data compressed by the data compression circuit 3 is written into the data buffer memory 4 one byte at a time. 8 is a first counting means, which indicates a data transfer created based on a response signal sent by the host device 1 every time 1 byte of data is transferred in response to a data transfer request sent by the control circuit 2 to the host device 1. Count the pulses.

Reference numeral 9 denotes a control means which totals the number of data blocks written on the magnetic tape based on the signal sent from the data compression circuit 3 indicating that data compression for l data blocks has been completed;
The count values of the counting means 8 and the counting means 7 are taken in for each data block, and are sequentially totaled, and the counting means 8 and the counting means 7 are reset respectively.

When the writing of data on the magnetic tape is completed, the control circuit 2 notifies the control means 9 via the data compression circuit 3. Based on this notification, the control means 9 uses the value A obtained by adding up the count value of the counting means 8, the value B adding up the count value of the counting means 7, and the total number C of data blocks written on the magnetic tape, ( Calculate the average compression ratio calculated by A/B)/C. Then, for example, it is displayed on the display section of the operator panel (not shown) and is notified to the host device 1 via the control circuit 2.

[Effect]

With the above configuration, the counting means 8 counts the number of bytes for each data block sent by the host device 1, and the counting means 7 counts the number of bytes for each data block compressed by the data compression circuit 3.

Then, the control means 9 totalizes the total number of bytes of data before compression and the total number of bytes of data after compression written on the negative volume of magnetic tape from the number of bytes counted by the counting means 7 and 8, In addition, since it is possible to determine the total number of data blocks written on the negative volume of magnetic tape from the compression completion signal of one data block sent out by the data compression circuit 3, the average compression ratio can be calculated. .

Therefore, the control means 9 can display the calculated average compression ratio on the operator panel of the magnetic tape device, etc., and can also send it to the host device 1 via the control circuit 2.

〔Example〕

FIG. 2 shows a circuit diagram showing an embodiment of the present invention.

FIG. 3 is a diagram illustrating the state of data block recording on the magnetic tape.

The host device 1 is, for example, a channel, and sends out a response signal in response to a data transfer request from the control circuit 2 of the magnetic tape device, and also sends out data blocks one byte at a time. The control circuit 2 transfers this 1-byte data to the data compression circuit 3.
At the same time, a pulse indicating 1-byte data transfer is sent to the counter 1) based on the response signal sent by the host device 1.

The data compression circuit 3 uses, for example, a run-length encoding method and a static encoding method to
Compress bytes of data sequentially.

Then, the compressed data is sent out to the data buffer memory 4 one byte at a time, and a write pulse is sent out to cause the data to be written into the data buffer memory 4.

The write circuit 5 reads the data written in the data buffer memory 4, sends it to the write head 6, and causes it to be written on a magnetic tape (not shown).

A counter 1) counts pulses sent out by the control circuit 2 indicating data transfer of 1 byte, and a counter 10 counts write pulses sent out by the data compression circuit 3 for each byte. Further, when the data compression circuit 3 is notified by the control circuit 2 that the transfer of one data block has been completed, it recognizes that data compression for one data block has been completed and sends a completion signal to the processor 12.

The processor 12 takes in the count values of the counters 10 and 1) based on this completion signal, and at the same time sends a reset signal to the counters 10 and 1) to clear the counters 10 and 1). Then, the count values of counters 10 and 1) are stored in the internal memory, and the number of data blocks written on the magnetic tape is stored as "1" in the internal memory.

In the same manner as described above, the counters 10 and 1) respectively count the number of bytes of the next data block, and the processor 12 converts the counted value of this data block into the value counted by the counters 10 and 1) respectively stored in the internal memory. At the same time, the operation of adding "1" to the number of data blocks stored in the internal memory is repeated.

Figure 3 shows the standard magnetic tape format, and ■
is the EOT indicating the beginning of the magnetic tape, ■ is the volume label VOL where the magnetic tape number is recorded, and ■
is the header HDR in which control information is recorded, ■ is the tape mark TM, and ■ is the EO indicating the end of the magnetic tape.
It is T.

The state in which the data block sent by the host device l is recorded as is is shown in Fig. 3 (al), ■ indicates the data block, and the state in which this data block ■ is compressed and recorded is shown in Fig. 3 (b). Yes, ■ indicates a compressed data block.

The data block ■ in FIG. 3(b) is compressed and occupies a smaller area on the magnetic tape than the data block ■ in FIG. The number of will increase.

When the control circuit 2 detects the EOT of the magnetic tape using a known method (not shown), it determines that writing of data to the magnetic tape is completed, and when the writing of the data block being processed is completed, the control circuit 2 determines that the writing of the data on the magnetic tape is completed, and when the writing of the data block being processed is completed, the control circuit 2 starts writing of the data for the next data block. A data transfer request is not sent to the higher-level device 1, and a completion notification is sent to the processor 12 via the data compression circuit 3.

When the processor 12 receives this notification of termination, it stores from the internal memory a value A that is the sum of the counts of counter 1), a value B that is the sum of the counts of counter 10, and a total number C of data blocks written on the magnetic tape. is read out, and the average compression ratio calculated by (A/B)/C is calculated, displayed on the display section of the operator panel (not shown), and notified to the host device 1 via the control circuit 2.

〔Effect of the invention〕

As explained above, when a data block is compressed and written to a magnetic tape, the present invention can display the compression ratio on the operator panel of the magnetic tape device, and also notify the host device of the compression ratio. It can be recorded as a computer console message, etc.

Therefore, the operator can easily recognize the compression ratio of data blocks written on the magnetic tape.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention, and FIG. 3 is a diagram illustrating the recording state of data blocks on a magnetic tape. In the figure, 1 is a host device, 2 is a control circuit, 3 is a data compression circuit, 4 is a data buffer memory, 5 is a write circuit, 6 is a write node, 7.8 is a counting means, 9 is a control means, 10 .1) is a counter, 1
2 is a processor.

Claims (1)

[Claims] A control circuit (2) that generates a pulse indicating data transfer based on a response signal sent by the host device (1) together with 1 byte of data, and a control circuit (2) that generates a pulse indicating data transfer. A data compression circuit (3) is provided which compresses and sends out each byte and also creates a write pulse for each byte and a compression completion signal for each data block, and the data compression circuit (3) compresses and sends out each byte. A recording device for recording a data block, the first counting means counting the number of bytes of the data block sent by the host device (1) based on a pulse indicating data transfer sent by the control circuit (2). (8), a second counting means (7) for counting the number of bytes of a data block to be compressed and written to a recording medium based on the write pulse created by the data compression circuit (3), and the data compression circuit (3)
Based on the compression completion signal sent by the storage device, the counting results of the first counting means (8) and the second counting means (7) are respectively aggregated in accordance with the total number of data blocks written on the recording medium. A recording apparatus characterized in that it is further provided with a control means (9) for calculating a data compression ratio from the total number of data blocks written on the recording medium.