JPH06103510A - Method for processing data of recording and reproducing device - Google Patents

Abstract

PURPOSE:To enhance efficiency in the reading operation of a recording and reproducing device and to improve processing speed. CONSTITUTION:By a DAT data storage device 23, backup for the memory contents in a hard disk 21 is performed. By SCSI bus 24, a host computer 22 is connected to the hard disk 21 and the data storage device 23. When a magnetic tape in the DAT data storage device 23 is read by the host computer 22, a space command and a read command are sent to the DAT data storage device 23 through the SCS(small computer system interface) bus 24, and the read data are stored in a buffer memory 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data processing method for a recording / reproducing device such as a magnetic tape device.

[0002]

2. Description of the Related Art A hard disk is widely used as an auxiliary storage device due to an increase in memory capacity, an increase in processing speed, and a reduction in price. A magnetic tape recording / reproducing device called a streamer is used in preparation for destruction of the memory contents of the hard disk. In recent years, a digital audio tape (hereinafter abbreviated as "DAT") data storage device has been used as a recording / reproducing device for backup of a hard disk. DAT
Although the data storage device has a large memory capacity and a relatively low price, it has a drawback that it takes a long time to find the beginning of the tape and the sequential access system is used, and the files cannot be randomly accessed.

FIG. 6 is a diagram showing the operation of the head when searching for data in a conventional DAT data storage device. The group 2 of data on the magnetic tape 1 is a minimum unit (about 128 kByte) at the time of reading and writing data, and the reference numeral 3 is desired data to be searched. When searching for data, the head of the DAT data storage device searches for a group containing desired data. When the group can be searched at the beginning of the group indicated by reference numeral 4, the data of the entire group 2 is read out and the operation of searching for the desired data is performed. When the reading of the entire group 2 is completed at the position of the reference numeral 5, the head of the DAT data storage device is relatively moved backward to execute the next command, and the head of the group including the desired data of the reference numeral 6 is read. 15 ~
Wait 20 frames before. This is the distance required to lock the tracking servo of the head when reading and writing the group 2 including the desired data.

FIG. 7 is a diagram showing the operation of the head when reading and writing in the DAT data storage device after searching for the desired data shown in FIG. In the example of FIG. 7A, after searching for desired data,
A write operation of data of groups 2 and 10 including desired data by a write command is shown. Figure 7
In the example of (b), after the desired data is searched, the read operation of the data of group 2 and group 10 including the desired data is shown by the read command. Reference numeral 11
The portion surrounded by the broken line is a read operation that is duplicated.

[0005]

In a recording / reproducing apparatus such as a conventional DAT data storage apparatus, when reading a magnetic tape, the entire group of data including desired data is read. The DAT data storage device stores the data in the buffer and retrieves the data. Next, the DAT data storage device relatively retracts the head and waits before the beginning of the group containing the desired data. In FIG. 7B, group 2 stores the data in the buffer at the first read. Because
The read instruction transfers data from the buffer. Therefore, the second read of the same group (group 2) does not read the data and runs in the reproduction (PLAY) state. Although the data is not actually read, the heads are moved redundantly, so that the read operation is wasteful and the efficiency is low.

It is an object of the present invention to provide a data processing method for a recording / reproducing apparatus which improves the efficiency of reading operation and improves the processing speed.

[0007]

According to the present invention, while displacing a medium relative to a head means, data detected by the head means is stored in a buffer memory for each predetermined unit amount, and In the data processing method of the recording / reproducing apparatus, which retrieves the desired data from the stored contents and processes the data following the retrieved data, after the desired data is retrieved, the next process is the reading of the data. At some time, the contents stored in the buffer memory are also used as data to be read, the medium is displaced relative to the head means to detect the data to be read next, and when the next processing is writing of data, the head is Positioning is performed by relatively displacing the medium in the direction opposite to the search direction with respect to the means, and then again displacing the medium relative to the head means. A data processing method of the recording and reproducing apparatus, wherein the writing data.

[0008]

According to the present invention, in the data processing method of the recording / reproducing apparatus, the medium is relatively displaced with respect to the head means when the read instruction is received following the search instruction from the central processing unit. Is searched for, a predetermined amount of data is detected, and the data is transferred to a buffer memory of a recording / reproducing device such as a DAT data storage device. The recording / reproducing apparatus searches the storage content of the buffer memory for data, and when the desired data is retrieved, uses the storage content of the buffer memory as the data to be read. Next, reading the data by the read command
When the data is recorded after the unit amount data including the desired data, the medium is relatively displaced with respect to the head unit to read the data. Therefore, the recording / reproducing apparatus does not duplicate the read operation between the head unit and the medium in response to the read instruction following the search instruction, so that the efficiency of the read operation can be improved. Since positioning is performed when writing data after the search, it is possible to write the data to be recorded on the medium including the searched data.

[0009]

1 is a block diagram showing a schematic electrical configuration of a computer system including a recording / reproducing apparatus according to an embodiment of the present invention. The hard disk 21 is an auxiliary recording device of the host computer 22 and stores programs, data and the like. The DAT data storage device 23 is a recording / reproducing device and backs up the memory contents of the hard disk in case of the destruction of the memory contents of the hard disk. A small computer system interface (hereinafter abbreviated as "SCSI") bus 24 was developed as a general-purpose magnetic disk device interface, and is generally used as an interface connecting a computer main body and an external storage device. . At present, the connection methods are standardized for magnetic disk devices, magnetic tapes, and optical disk devices. SC
A total of up to eight devices can operate on the SI bus 24, and the devices are classified into an initiator and a target. The initiator is a device that issues a command, and the target is a device that receives and executes the command. In the example of FIG. 1, the host computer 22 is the initiator,
The DAT data storage device 23 becomes the target.

In the DAT data storage device 23,
A microcomputer 25, a DAT signal processing circuit 26,
A DAT mechanism 27, a SCSI controller 28 and a buffer memory 29 are included. SCSI controller 28
Is connected to the SCSI bus 24, and the microcomputer 25 and the DAT signal processing circuit 2 are connected via the internal data bus.
6 and the buffer memory 29. The DAT signal processing circuit 26 processes a signal to be written in or read from the DAT mechanism 27. Microcomputer 25
Controls the operation of the DAT data storage device 23.

In the SCSI bus 24, there is a use state of a bus called a phase, and it is basically divided into five, a bus free phase, an arbitration phase, a selection phase, a reselection phase and an information transfer phase. . The bus free phase is
The SCSI bus 24 is not using any device. Arbitration phase is SCSI bus 2
In the selection phase, the initiator having the usage right selects a target. The information transfer phase includes phases such as command, data and status. The command phase sends a command from the initiator to the target, the data phase transfers data, and the status phase notifies the initiator of the execution result of the command.

FIG. 2 shows a 6-byte format command 30 sent from the initiator to the target in the command phase, and the entire command 30 is transferred.
In the command code 31 of the lower 5 bits of the 0th byte,
Operation codes such as Read, Write, and Space are specified. The Read command reads a data block, and the Write command writes a data block. The Space command moves the specified amount of media in the forward or reverse direction by the number of blocks. The LUN field 32 is a field for designating the logical unit number (LUN) of the command issue destination. The logical block address field 33 specifies the leading logical block address of the data block to be processed. The transfer data length 34 is a field that specifies the amount of data to be processed by the command in the number of logical blocks or the number of bytes. When the value of the link bit 36 is "1", it indicates that the commands are continuously issued. The target sends a message corresponding to the value of the flag bit 37 when the command when the value of the link bit is "1" is normally completed. Reserve Field 38
Is a command reserved for future specification expansion.

The vendor unique field 39 is a field whose specifications are released, and the meaning can be uniquely defined for each device. In this embodiment, reference numeral 40
The operation contents after execution of the Space command are assigned as shown in. For example, when the 7th bit of the vendor unique field is "0" and the 6th bit is "1", it indicates that the Read command is executed after the Space command is executed.

FIG. 3 shows an embodiment of the present invention, which is the DA of FIG.
9 is a flowchart showing the processing contents when a Space command and a Read command are executed consecutively in the T data storage device 23. In step a1, command execution processing is started. DA in step a2
The T data storage device 23 is the host computer 22.
2 is received, and the command code 31 is 11H (hexadecimal number), it is decoded as a Space command. Further, since the code of the vendor unique field 39 is 01B (binary number), it can be interpreted as a Read command, and it can be determined that the Read command is executed after execution of the Space command. In step a3, Space
Executes the command, and the DAT data storage device 23
Searches for a group containing desired data. When the group can be searched, the entire group is read and the read data is sequentially stored in the buffer of the DAT data storage device 23. The DAT data storage device 23 performs a process of searching for desired data from the data stored in the buffer. After the processing is completed, the next command is understood to be the Read command, so the head of the DAT data storage device 23 is made to wait at the last position of the group. In step a4, the DAT data storage device 23 receives the Read command. In step a5, although the Read command is executed, since the data of the group including the desired data is stored in the buffer, that data is used. Therefore, the number of groups designated by the command is read from the group next to the group containing the desired data. However, in the case of a read command for one group, the read operation is not performed because the data in the buffer can be used.

FIG. 4 is a diagram showing the operation of the head of the DAT data storage device 23 when the flowchart of FIG. 3 is executed. DAT storage device 23 is Space
Vendor Unique
From the field, it can be determined that the next command is the Read command. After detecting the label of the group 50 at the position of the reference numeral 51, the head of the DAT data storage device 23 reads the data of the group 50 and searches for the desired data. DAT data storage device 23
Receives the Read command at the position of reference numeral 52 and performs the read operation of the next group 53.

FIG. 5 shows another embodiment of the present invention, which is shown in FIG.
9 is a flowchart showing processing when a Space command and a Read command are continuously executed in the illustrated DAT data storage device. D in step b1
The processing of the AT data storage device is started. In step b2, the DAT data storage device 23 receives the command 30 shown in FIG. 2 from the host computer 22, and if the command code 31 is 11H (hexadecimal number), it is interpreted as a Space command. Here, if the command code 31 is other than the Space command, the command is executed in step b3, and the process ends in step b9. In this embodiment, since the vendor unique command 39 is not used, the contents of the next command cannot be known in advance after executing the Space command. Therefore, in step b4, the DAT data storage device 23 requests the next command from the host computer 22. At step b5, if the DAT data storage device 23 receives the Read command as a result of requesting the next command,
You can judge that Space command and Read command are executed consecutively. As a result, in step b6, the DAT data storage device 23 uses the contents described in FIG.
After executing the e command, the Read command is executed, and the process ends in step b9. If the command received by the DAT data storage device 23 is other than the Read command in step b5, the Space command is executed in step b7, the command having the code content received in step b8 is executed, and the process ends in step b9. To do.

Although the DAT data storage device has been described above, it goes without saying that the DAT data storage device may be applied to a recording / reproducing device using another magnetic tape or magnetic disk as a recording medium.

[0018]

As described above, according to the present invention, in the data processing method of the recording / reproducing apparatus, the reading process following the search can be performed without overlapping the relative movement of the medium with respect to the head means. In that case, since the recording / reproducing apparatus stores a predetermined unit amount of data including the retrieved desired data in the buffer memory, the memory content is used as the data to be read. The relative movement between the head means and the medium is performed for the next unit amount data to be read. Therefore, since the reading operation is not repeated, the efficiency of the reading operation of the recording / reproducing apparatus can be improved, and the processing speed can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic electrical configuration of a computer system including a recording / reproducing device according to an embodiment of the present invention.

FIG. 2 shows the contents of a command sent from a host computer to a DAT data storage device.

FIG. 3 is a flowchart showing a process when a Space command and a Read command are continuously executed in the DAT data storage device shown in FIG. 1 in an embodiment of the present invention.

FIG. 4 is a flow chart showing D
It is a figure showing a movement operation of a head of an AT data storage device.

5 is a block diagram illustrating a Space command and a Read command in the DAT data storage device shown in FIG. 1 according to another embodiment of the present invention.
It is a flowchart which shows the process in case a command is performed continuously.

FIG. 6 is a diagram showing the operation of the head when searching for desired data in a conventional DAT data storage device.

FIG. 7 is a diagram showing the operation of the head when reading and writing after searching for the desired data shown in FIG. 6 in the conventional DAT data storage device.

[Explanation of symbols]

 21 hard disk 22 host computer 23 DAT data storage device 24 SCSI bus 25 microcomputer 27 DAT mechanism 29 buffer memory 30 command 31 command code 33 logical block 34 transfer data length 36 link 37 flag 38 reserve 39 vendor unique field

Claims (1)

[Claims] 1. Displacement of a medium relative to a head means, data detected by the head means is stored in a buffer memory for each predetermined unit amount, and desired data is stored in the buffer memory. In the data processing method of the recording / reproducing apparatus for searching for the data and processing the data subsequent to the searched data, when the next processing is the reading of the data after the desired data is searched, the storage content of the buffer memory Is also used as data to be read, the medium is relatively displaced with respect to the head means to detect the data to be read next, and when the next process is writing of data, the medium is searched with respect to the head means. In contrast to the above, the positioning is performed by relatively displacing in the opposite direction, and the medium is again displaced relative to the head means to write data. The data processing method that the recording and reproducing apparatus.