JPH053610B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a magnetic tape device for recording and reproducing a magnetic tape on which a plurality of file information is recorded, and particularly relates to a magnetic tape device that records data sequentially in the longitudinal direction of a magnetic tape. It relates to tape devices.

[Technical background] Magnetic tape devices have a low cost per unit storage capacity, but they record and reproduce data sequentially in the longitudinal direction of a magnetic tape. To access desired data, it is necessary to read data sequentially from the beginning of the magnetic tape. I need to find the data. Therefore, the access speed of the magnetic tape device is extremely slow, making it unsuitable as a storage device for storing data that is frequently accessed.
Therefore, magnetic tape devices are generally used for backing up DASDs such as magnetic disk devices. That is, data is searched and updated on DASD, and this data is recorded and stored on magnetic tape.

On the other hand, it is a library file that can access data at high speed like DASD, yet maintains low cost per unit storage capacity like magnetic tape devices, and can search data at high speed. A mass storage storage system (MSS) has been developed for use. However, this MSS is currently only applied to large-scale systems and is still expensive.

[Conventional technology and problems]

As a lower cost magnetic tape device, there is a magnetic tape device called a serpentine type magnetic tape device. FIG. 11 explains the data recording system in a magnetic tape device called the serpentine system, in which MT represents the magnetic tape, BOT represents the beginning of the tape, and EOT represents the end of the tape. Also, the arrow indicates the head locus. When writing data to or reading data from a magnetic tape, the head is positioned on a track at the beginning of the tape, moves forward on track 1, is positioned on track 2 at the end of the tape, and moves forward on track 2. The tape moves in the opposite direction, is positioned on track 3 at the beginning of the tape, and moves forward on track 3. Thereafter, similar operations are repeated.

Since the serpentine magnetic tape device uses one magnetic head during recording and reproduction, it has the characteristic that it is inexpensive, requiring only one read/write circuit for one channel. in this case,
The data is arranged in the longitudinal direction of each track, that is, the data is arranged and recorded in series on one track. Therefore, when a plurality of pieces of file information are recorded, it is not possible to absolutely determine the recording position of each piece of file information. In other words, file information is a series of data sets, but the data length of each piece of file information is variable. Therefore, in order to access the desired file information, data must be read from the beginning of track 1, and the data length of each piece of file information is variable. Therefore, the magnetic tape cannot be driven at high speed to the recording position of the desired file information. In this way, in order to track the target file information, it is necessary to move the head back and forth in the longitudinal direction of the magnetic tape many times, which has the disadvantage that it takes time to access the information. Particularly in the case of multi-files, that is, when a plurality of file information are recorded on one magnetic tape, it takes a long time to access files recorded at the rear.

Serpentine type magnetic tape devices suffer from the above-mentioned drawbacks. Furthermore, even with ordinary magnetic tape devices, index information called tape marks (TM) is only recorded at the delimiter of each file information, and in order to access the desired file information, the tape marks must be read sequentially. Therefore, the magnetic tape cannot be driven to the recording position of the target file information at high speed, and access takes time.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, an object of the present invention is to provide a recording system for a serpentine magnetic tape device that allows efficient access to desired file information recorded on a magnetic tape. Another object of the present invention is to provide a method for accessing a serpentine magnetic tape device for use as a library file at a lower cost than MSS.

[Structure of the invention]

Therefore, the recording method of the magnetic tape device, which is the first invention of the present invention, is a serpentine method in which a plurality of pieces of file information are sequentially recorded in the longitudinal direction of the magnetic tape in units of file information, which is a collection of a series of data. In the magnetic tape device, the magnetic tape is provided with a directory area and a data area, the file information is recorded in the data area, and at least the file name and the beginning of the file information are recorded as management information of the file information. The present invention is characterized in that the number of the track on which the file is located and the distance information from the reference position on the magnetic tape to the recording position of the file information are recorded in the directory area.

First, in the access method for a magnetic tape device, which is the second aspect of the present invention, a plurality of pieces of file information are recorded in a data area of a magnetic tape in units of file information, which is a collection of a series of data, and the file information is A serpentine method in which at least the file name, the number of the track where the beginning of the file information is recorded, and the distance information from the reference position on the magnetic tape to the recording position of the file information are recorded in the directory area of the magnetic tape as management information. In this magnetic tape device, when a higher-level device accesses the magnetic tape, it reads management information in the directory area and creates a management table, and the higher-level device refers to the management table and stores the management information of desired file information. The information is sent to the magnetic tape device, and the magnetic tape device positions the magnetic tape at a recording position of the desired file information based on the management information.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 shows an example of a read/write head. This figure shows the read/write head viewed from the magnetic tape side. In Figure 2, HD
is the read/write head, R is the read head gap, W is the write head gap, and E is the erase head gap. The head set consisting of the read head, write head, and erase head in the first row is used in the forward direction (direction of arrow a), and the head set consisting of the read head, write head, and erase head in the second row is used in the forward direction (arrow a direction). The head set consists of the opposite direction (arrow b
direction). For example, in the case of a 24-track magnetic tape, the width of the head set in the first row and the width of the head set in the second row is 2 when the head set in the first row is located on the first track from the top. The head set of the row is determined to be located on the 13th track from the top. Instead of read/write heads as in Figure 1, there are E, R, W, R, E in one line.
It is also possible to use an arrangement of read heads, write heads and erase heads such that:

FIG. 2 shows a recording format of management information and data on a magnetic tape according to the present invention.
In Figure 2, T ₁ , T ₂ ,... are tracks;
Tracks are called first, second, etc. in order from the top, _P1 indicates the directory starting point, and _P2 indicates the data starting point of track 1, respectively. Here, P ₁ and P ₂ are shown in Figure 2 for convenience of explanation, but nothing is recorded in the following explanation, and the distance traveled by the tape is confirmed by counting tacho pulses. Assume that P ₁ and P ₂ are detected. The magnetic surface of the magnetic tape MT is divided into a directory area and a data area. In this example, as shown in Figure 2, the directory area is given a fixed length area behind the BOT, and from the back of this directory area
The data area is up to EOT. The directory starting point P ₁ is located on the track T ₁ at a certain distance from the tape starting end BOT, and the data starting point P ₂ of the track T ₁ is located at a certain distance from the tape starting end BOT. Tracks T ₁ , T ₂ , in the data area
...Tp is divided into a plurality of track groups each consisting of n tracks (n is a natural number), for example, two tracks. When n=2, tracks T ₁ and T ₂ of the data area constitute a first track group, and tracks T ₃ and T ₄ constitute a second track group. Each directory area contains multiple tracks.
A plurality of directory sections are provided in one-to-one correspondence with each group. If n=2,
Tracks T ₁ and T ₂ of the directory area constitute the first directory part, and tracks T ₃ and T ₄ constitute the second directory area.
It constitutes the directory part of. Here, tracks T ₁ , T ₃ . . . are called first tracks of the track group, and T ₂ , T ₄ are called second tracks. The same applies hereafter. The i-th directory section records management information for the i-th track group. The magnetic head follows the trajectory indicated by the arrow in the figure in the directory area, and further follows the trajectory indicated by the arrow in the figure in the data area.

FIG. 3 shows the recording format of data in the track group of the data area. In FIG. 3, TM indicates tape mark. Serial numbers such as 0, 1, 2, etc. are recorded on each tape mark. A file name is recorded on the file, then data is recorded, and a tape mark TM is recorded at the end of the file. It is possible to record multiple file information in one track group, but only one
One file information is never recorded across two track groups. Also, a track group may be formed for each file.
That is, track groups are formed such that only two files are always present in one track group. In this case, the number of tracks in each track group will be different.

FIG. 4 explains the management information recorded in the directory section. The directory section contains information indicating the name of the file recorded in the corresponding track group, the number of the track where the beginning of the file is located, the tape mark serial number, and the distance from the beginning of the tape to the beginning of the file (for example, reel The winding diameter of 14 and 15 and the number of tacho pulses are recorded. This directory section is also recorded in the same format as normal data, and an IBG exists between the directory sections of each track group. In this way, set the recording position of the file information to the reference position (BOT mark).
If the distance from the magnetic tape is expressed as distance information and the amount of movement of the magnetic tape is monitored, the target file information can be accessed at high speed.

Next, Sections 5, 6, and 7 will be explained regarding the configuration of a magnetic tape device for recording data on a magnetic tape and reproducing data on a magnetic tape.
This will be explained with reference to the block diagram shown in the figure. Fifth
The figure shows the overall configuration of a magnetic tape device for recording and reproducing magnetic tape of the above-described recording format.
In the figure, 1 is an interface circuit, 2 is a data buffer, 3 is a command decoder, 4 is a format generator, 5 is an encoder, 6 is a decoder,
7a is a write data check circuit, 7b is an error detection and correction section, 8a is a status holding section, 8b is a sense data holding section, 9 is a control circuit, 10 is a reel motor control section, 11 is a head position control section,
12 is a light amplifier, 13 is a lead amplifier,
14 is a supply reel, 14' is a tape winding amount detection section of the supply reel, 15 is a take-up reel, 15' is a tape winding amount detection section of the take-up reel, 16 and 17 are reel motors, and 18 is a read/output reel. The write head 19 indicates a head moving mechanism, respectively.

The interface circuit 1 is for exchanging data with an upper host computer. The data buffer circuit 2 temporarily holds write data sent from a higher-level device, and temporarily holds read data to be sent to a higher-level device. The command decoder 3 decodes commands sent from the host device. The format generating section 4 generates format information, error detection and correction codes, check bits for reading and checking written data with a reading head, and the like. The encoder 5 modulates data. It uses error detection and correction codes (ECC code, CRC, etc.) to detect and correct errors. The status section 8a holds status information to be sent to a higher-level device, and the sense data holding section 8b holds sense data to be sent to a higher-level device. The control circuit 9 controls the entire magnetic tape device, and is composed of a microprocessor. The reel motor control section 10 is
The reel motors 16 and 17 are controlled so that the tension and speed of the magnetic tape are constant. Signal MOVE is a movement instruction, signal FWD/
BWD is a direction instruction, that is, a forward or reverse feed instruction, and a signal TACHO is a tacho pulse of a number proportional to the rotation speed of the reel motors 16 and 17, which is output from a tachogenerator provided in the reel motors 16 and 17. shows. The head position control section 11 controls the head movement mechanism 19. Signal SHIFT is a shift instruction, signal UP/
DOWN indicates the direction, and the signal POSTION indicates the head position. The write amplifier 12 amplifies the modulated write data. Signal SELECT indicates head group selection, signal SWRS
is a write state set instruction, which is a command for causing a write current to flow through the write head, and signal WRS indicates whether or not it is in the write state, that is, the response to SWRS. Read amplifier 13 is read/write head 18
It amplifies the analog read data from. Reel motor 16 drives supply reel 14, and reel motor 17 drives take-up reel 15. As mentioned above, the read/write head 18 includes one or more head sets consisting of an erase head, a write head, and a read head. Head movement mechanism 19 is for positioning read/write head 18 on the track.

Regarding the process of recording data in the data area and directory area according to the recording format shown in FIG. 2 in a magnetic tape device with the above configuration, first let's look at the circuit diagram of the magnetic tape device in FIG. This will be explained with reference to the flowchart shown in FIG.
In this case, it is assumed that one track group is composed of two tracks. First, a case in which file information is recorded in a data area on a magnetic tape will be described with reference to the flowchart shown in FIG. 8a.

When the host device issues a command, the interface circuit 1 receives the command and transfers it to the command decoder 3. This write command includes the file name of the file information to be recorded, the data length of the file information, and the like as parameters.

The command decoder 3 decodes the contents of the command and sends the contents to the control circuit 9. In this case, the following description will be made assuming that this is a write command for recording new file information on the magnetic tape M9. When the control circuit 9 receives the write command, it transmits a status indicating that the write command has been received to the status section 8a, and this status is sent to the status section 8a.
The information is reported to the higher-level device via the interface circuit 1. Then, TM (tape mark serial number) N0 is set to 0.

Next, the control circuit 9 checks the drive status. That is, before receiving the write command described above, it is recognized which file on the magnetic tape M9 the magnetic head 18 is positioned, and the MOVE command and FWD/BWD command to the reel motor control unit 10 and head position control are executed. SHIFT command for part 11 and
Set UP/DOWN command. Then, the magnetic head 18 is positioned at the beginning _P2 of the data area of the first track in the track group.
That is, when recording file information for the first time, it is positioned at the beginning of the data area of the first track.

Furthermore, the control circuit 9 sets track N0 to the number of the track on which the transferred file information is to be recorded, and sets the number of the track group.

When the above processing is completed, a status requesting data transfer of write data is sent to the host device. The host device that received this status is
Transfer data to a magnetic tape device. In this case, data is transferred in file information units.
A file name is added to the beginning of each piece of file information, as shown in FIG. The transferred data is sent to interface circuit 1.
The data is first stored in the data buffer 2 via the . The data transferred in this data buffer 2 is divided into data blocks of several bytes.

The control circuit 9 includes a reel motor control section 10
to start tape movement for
Instruct by MOVE command and FWD/BWD command. Further, it sends a SELECT signal to the write amplifier 12 for selecting a head group, and also sends a SWRS signal for setting the state of an analog circuit such as an amplifier to generate a write current. In this case, the track
The head set selected for recording from the beginning of No. 1 is the upper head set shown in FIG. The write amplifier 12 sends a WRS signal to the control circuit 9 when the write current becomes capable of being output regularly. In other words, the write timing is determined by reception of the WRS signal.

The control circuit 9 that received the WRS signal confirms from the TACHO signal that the magnetic tape M9 is running at a constant speed, and sends the format to the format generator 4.
First, data for preamble generation is output. The encoder 5 is a format generator 4
The input preamble is modulated into write data and sent to the write amplifier 12. Thereafter, data is sequentially transferred from the data buffer 2 in block units, and the encoder 5 modulates these data into write data. In addition to this, the format generating section 4 adds an ECC code, a check bit for checking data at the time of reading, a postamble, etc. to the data transferred block by block.

When the control circuit 9 starts writing file information, it sets TMN0, track N0, track group N0, and the recording start position of the file information using the value of the tacho pulse counter, which is then transferred as a command parameter from the host device. Based on the received file name, management information of the file information to be recorded is generated and held as sense data in the sense data holding section 8b. The data written on the magnetic tape M9 is immediately read by the read head, amplified by the read amplifier 13, and then the check bit added at the time of writing is decoded by the decoder 6 and sent to the check circuit 7a. will be checked. If an error is detected in the check circuit 7a, the error is reported to the control circuit 9. Since error detection is performed block by block, the control circuit 9 sends a signal to the reel motor control unit 10 to position the magnetic head 18 at the beginning of the block where the error has occurred, and rewinds the magnetic tape M9 by one block. Execute rewrite or retry. The data of this block is still held in the data buffer 2, and the data of this block is read out from the data buffer 2 again and written in the above-described procedure.
If no error is detected by the check circuit 7a, the next block is stored in the data buffer 2 and writing continues.

' When the host device indicates that the transfer of one file information is completed and the read check is also completed, the status data and sense data at the end of writing are created to report the completion of writing one file information, and the sense data created earlier is It is sent to the higher-level device along with management information. The host device creates a management table in the format shown in FIG. 4 based on the transferred management information.

If there is more file information to be recorded, the process moves to step . If not, data writing ends.

The control circuit 9 includes a tape winding amount detection section 14', 1
The data length that can be recorded in the data area of the same track is calculated from the tape winding amount detected from 5' and compared with the data length of the next file information to be recorded that was transferred at the same time as the command.
If it is determined that recording is possible in the same track group, the following process (TM number plus 1) is performed. Further, the process moves on to processing if recording is not possible in the same track group.

As described above, file information is recorded in the data area on the magnetic tape.

When the recording of the data area is completed, the host device records the contents of the created management table (management information) in the directory area of the magnetic tape. The process for recording this management information in the directory area will be explained with reference to the flowchart of FIG. 8b.

When the host device writes the contents of the management table to the directory area, it first performs WRITE.
Issue a DIRECTORY command. The host device then sends the track group number and track number as parameters before sending the management information for each file information. Management information is transferred in track group units, so
It is recorded from the end of the track in the directory area, and the aforementioned parameters (track group number, track number) are transferred prior to transferring the management information of each track group.

The WRITE DIRECTORY command is decoded by the command decoder 3 and transferred to the control circuit 9.

The control circuit 9 sets the track group number G and track number t based on the transferred parameters. In this case, since the management information of all track groups is recorded in the directory area, G = 1, t = 1, and eventually BOT
The magnetic head 18 is rewound to this position, and the head set for forward recording of the magnetic head 18 (the head set in the upper row of FIG. 1) is positioned on the first track.

The drive status is checked and set in order to control the head position control section 11 according to the track group number G and the track number t to position the magnetic head 18 at a track position corresponding to a predetermined track group. . When a track group is composed of two tracks, the first track of the corresponding track group is positioned on the BOT side.

When the positioning is completed, the same process as in FIG. 8a is performed.

Then, a value corresponding to the predetermined recording length of each track in the directory area is preset in the tacho pulse counter.

Record the transferred management information.

When the recording of management information for one track is completed, the process moves on to processing. If it has not finished, move on to processing.

If there is no management information to be recorded next, the process ends and recording of the directory area is completed. If so, move on to processing.

Next, if the track group G' of the management information to be recorded is equal to the track group G set in , the process moves to , and the data is recorded directly. If G≠G', the process moves to step .

G≠G′ means that the next management information has a different track group.
The track group number G is incremented by 1, and the track number t is further incremented by 1, and the process proceeds to the next step.

If the writing of management information for one track group is not completed, the control circuit 9 detects whether a carry signal is generated from the tacho pulse counter. That is, the occurrence of a carry signal from the tacho pulse counter indicates that the magnetic head 18 is located at the end of the track in the directory area. If a carry signal is generated, the process moves on to processing; otherwise, the process moves on to data recording.

The track number t is incremented by 1 and the process moves on.

Management information is recorded in the directory area as described above.

Next, control of magnetic tape positioning and head position movement control using tacho pulses will be explained with reference to a detailed block diagram of the reel motor control section 10, head position control section 11, and write amplifier 12 in FIG. .

6 is a detailed view of the reel motor control section 10 shown in FIG. 5, and FIG. 7 is a detailed view of the head position control section 11 shown in FIG. In the figure, the same parts as in FIG.
2 is an AND circuit into which the MOVE command of the control circuit 9 and the output of the FF 20 are input; 23 is a comparator that determines whether the rotational speed of the reel motor 16 is increased or decreased; 24
25 is a motor drive circuit that supplies rotation drive current to the reel motor 16 in accordance with the selection signal of the comparator 23; A motor drive circuit that supplies rotational drive current to the reel motor 17; 29 is a counter corresponding to the reel motor 16; 30 is a counter for the reel motor 17;
27 is a counter corresponding to , which counts the tacho pulses of a tacho generator (not shown) which are output, for example, three times per revolution of the corresponding reel motor; 27 decodes the count value of the counter 29 and sends it to the control circuit 9; 28 is a decoder that decodes the count value of the counter 30 and sends it to the control circuit 9. 29' is a timer that measures the time between two tacho pulses and detects the rotation speed of the reel motor 16. 30' is a decoder that decodes the count value of the counter 30 and sends it to the control circuit 9. A timer 27' detects the rotation speed of the reel motor 17 by measuring the time between two tacho pulses, and a timer 27' decodes the output of the timer 29' and sends it to the control circuit 9.
28' is a decoder that sends out the rotation speed of timer 3.
0' output is decoded and reeled to the control circuit 9.
a decoder 14' that sends out the rotational speed of the motor 17;
15' is a tape winding amount detection section that detects the amount of tape wound on the tape reel 14; 15' is a tape winding amount detection section that detects the amount of tape wound on the tape reel 15; 27''; and 28'' are decoders that decode the winding amount detected by the corresponding tape winding amount detection section and send it to the control circuit 9, and 34 and 35 are decoders that are output from the head moving mechanism 19, for example, from a pulse motor. A/D converters 32 and 3 that convert the position signals of
3 decodes the outputs of A/D converters 34 and 35, respectively, and indicates the position of the magnetic head.
A decoder sends the POSITION signal to the control circuit 9; 36 is a flip-flop to which the magnetic head upward/downward movement instruction signal (UP/DOWN) output from the control circuit 9 is input; 37 and 38 are input from the control circuit 9. An AND circuit into which the output head movement instruction signal (SHIFT) and the output signal of the FF 36 are input; 45 is a counter that measures the output time of the AND circuit 37; 46 is a counter that measures the output time of the AND circuit 38; 47 is a counter A drive circuit 48 outputs a drive signal for driving the pulse motor of the head moving mechanism 19 to move the magnetic head 18 in one direction by an amount corresponding to the measured value of the counter 46; A head moving mechanism 19 moves the magnetic head 18 in the other direction.
39 is a control circuit 9 for selecting one of the two head sets as shown in FIG.
40 is a write current generation circuit that outputs a write current to the magnetic tape M9 in accordance with the data converted into a write signal by the encoder 5; 41; is a switching circuit which switches the destination of the output current of the write current generating circuit 40 in accordance with the output of the selection circuit 39 and supplies it to either of the two magnetic head sets.
The control circuit 9 detects the current magnetic tape position as follows. Counters 29 and 30 count tacho pulses output from tachometers (for example, those that output three tacho pulses per one rotation of the motor) provided on the reel motors 16 and 17. The count values of counters 29 and 30 are decoded by decoders 27 and 28. That is, the outputs of the decoders 27 and 28 represent the amount of movement of the magnetic tape. Also, timer 2
9' and 30' measure the time between input of two tacho pulses to detect the rotational speed of the reel motors 16 and 17. The detected values of the timers 29' and 30' are decoded by decoders 27' and 28', and signals corresponding to the rotational speeds of the reel motors 16 and 17 are input to the control circuit 9. Tape winding amount detection section 14', 1
The output signals 5' represent the tape winding amounts of the supply reel 14 and the take-up reel 15, respectively, and by decoding these signals with decoders 27'' and 28'', the current status of the two reels is sent to the control circuit 9. The tape winding amount is sent out. Therefore, if the tape winding amount and the reel motor rotation speed when the tape is running at a constant speed are known in advance, this and the decoder 2
By comparing the values input from 7, 28, 27', and 28', it is possible to detect whether the tape is running at a constant speed. Further, when the tape is not running at a constant speed, the control circuit 9 calculates and determines the amount of increase or decrease in the rotational speed of the motor to make the tape run at a constant speed, and this value is determined by the motor drive circuits 25 and 26.
is converted into an output current value of D/A converter 23, 2.
Enter into 4. Thereby, the control circuit 9 inputs a signal to the D/A converters 23 and 24 to speed up or slow down the reel motors 16 and 17 by a predetermined amount. The outputs of the D/A converters 23 and 24 are output from motor drive circuits 25 and 26. When the reel motor drive current is increased or decreased, the control circuit 9
Signals representing the rotational speed of the reel motors 16 and 17, the amount of movement of the magnetic tape, and the amount of tape winding of the tape reels 14 and 15 are input to the . When the magnetic tape runs at a constant speed, the tape winding amount of the tape reels 14 and 15 and the reel motor 1
The rotational speeds 6 and 17 correspond one to one. Therefore, the control circuit 9 adjusts the reel and
Motor drive currents for obtaining the rotational speeds of motors 16 and 17 are calculated, and these values are input to comparators 23 and 24, respectively. The comparators 23 and 24 are
The motor drive current values currently output by the motor drive circuits 25 and 26 are compared with the motor drive current value output by the control circuit 9, and the reel motors 16 and 1 are
7 and selectively outputs a signal to the motor drive circuits 25 and 26 to increase or decrease the output power current value for driving the motor. As a result, the reel motor 16,
The rotation speed of 17 is controlled so that the magnetic tape runs.

Distance information between the reference position, which is one of the management information, and the recording position of the file information is obtained by counters 29 and 30. For example, take the BOT position as the reference position. At this BOT position, the value of the tacho pulse counter 29 of the reel motor 16 on the supply reel side is set to 0, and the value of the tacho pulse counter 30 of the reel motor 17 on the take-up reel side is set to 10,000. In other words, when the magnetic tape is moved from BOT to EOT, 10,000 tacho pulses are output, and the recording position on the magnetic tape can be set according to each count value. Therefore, in the data area, the values of the tacho pulse counters 29 and 30 at the start of recording of each file information become distance information indicating the recording position, and the control circuit 9 manages the data output of this counter value when recording data. It is held as information in the sense data holding unit 8b shown in FIG. 5, and when recording of one file information is finished, this management information is transferred as sense data to the host device. When positioning the magnetic tape to a predetermined file information recording position, the control circuit 9 presets this distance information in the counters 29, 30 as management information, and when a carry signal is generated, the control circuit 9 presets the distance information in the counters 29, 30. All you have to do is stop the rotation and position it. Note that the MOVE signal and FWD/BWD signal output from the control circuit 9 are signals for controlling the moving direction of the magnetic tape M9. In other words, in Fig. 6, when driving the reel motors 16 and 17, always MOVE
Set the signal to logic ``1'' and insert the magnetic tape M.
To move the flip-flop 9 in the forward direction, the FWD/BWD signal is set to logic "1" and input to the flip-flop (FF) 20. Therefore, the output of the AND circuit 21 becomes logic "1" and the reel motor 16,1
Rotate 7 forward. Conversely, in order to move the magnetic tape M9 in the opposite direction, set the FWD/BWD signal to logic "0" and input it to FF20, FF20 is reset and the output of AND circuit 22 becomes logic "1".
Then, the reel motors 16 and 17 are reversed.

Next, how the head position control section 11 performs movement control using the magnetic head shown in FIG. 1 will be explained in detail with reference to FIG. 7. The magnetic head shown in FIG. 1 has an upper magnetic head set for forward recording/reproduction and a lower magnetic head set for reverse recording/reproduction. is driven to move the magnetic head 18 up and down. Movement of the head can be realized, for example, by using a step motor. The SHIFT signal and UP/DOWN signal output from the control circuit 9 are signals for operating the head moving mechanism 19.
In other words, when moving the magnetic head 18 in the a' direction, the SHIFT signal is set to logic "1" and the UP/
Set the DOWN signal to logic "1" and input it to FF36. Therefore, the output of the AND circuit 37 becomes logic "1", the counter 45 counts the output time of the AND circuit 37, and inputs the count value to the drive circuit 47. The drive circuit 47 outputs a number of pulse signals corresponding to this count value to drive the step motor of the head moving mechanism 19 in the forward direction, thereby moving the magnetic head 18 in the a' direction. Conversely, to move the magnetic head 18 in the b' direction, the SHIFT signal is set to logic "1" and the UP/DOWN signals are set to logic "0". Therefore, the output of the AND circuit 38 becomes logic "1". A counter 46 counts the output time of the AND circuit 38, and when this count value is input to a drive circuit 48, a number of pulses corresponding to the count value is output to the step motor of the head drive mechanism 19. The step motor rotates in reverse according to the number of pulses, and the magnetic head 18
Move in direction b′. The step motor outputs the current step position, that is, the current magnetic head 1.
A signal representing the position of 8 is input to A/D converters 34 and 35. The A/D converted signal representing the step motor position is decoded by decoders 32 and 33 and sent to the control circuit 9 of the magnetic head 18.
Input as POSITION signal. Therefore, the control circuit 9 uses the POSITION signal to identify the track on which the magnetic head 18 is currently positioned, and identifies the track to be positioned (the track among the management information given as a parameter of the command).
Calculate how many steps the step motor needs to be rotated forward or reverse in order to position it at
The output time of the SHIFT signal is determined by the number of steps, and the forward/reverse rotation (UP, DOWN) of the step motor is instructed by the UP/DOWN signal.

Next, the write amplifier 12 will be explained.
In this embodiment, as described above, there are two magnetic head sets, so when moving the magnetic tape M9 in the FWD (forward) direction, the upper head set is selected as shown in FIG. ) direction magnetic tape M9
When moving, select the lower head group.
The control circuit 9 sends the SELECT signal to the selection circuit 39. At the same time, the write current generation circuit 40
Sends the SWRS signal to set the write current generation state. In response to the SELECT signal, the selection circuit 39 causes the switching circuit 41 to switch the signal line in order to supply the write current output from the write current generation circuit 40 to either head group. When the SWRS signal is supplied to the write current generation circuit 40, since this circuit is an analog circuit, it does not become ready to output a write current immediately, but takes a certain amount of time. Therefore, the write current generation circuit 40 uses SWRS.
After receiving the signal and setting the write current generation state after a certain period of time has elapsed, the WRS signal is input to the control circuit 9. When the control circuit 9 receives the WRS signal,
A signal is sent to the encoder 5 and the modulated write current is transferred to the write current generator 40. A SELECT signal instructing the selection of a head set is sent after identifying whether the track is to be recorded or reproduced in the forward direction or the reverse direction, based on the track number in the management information.

As described above, the control circuit 9 positions the magnetic head at a predetermined recording position using the distance information and track number included in the management information.
This is done by controlling the amplifier 12. When positioning completion is detected by the P0SITION signal, the MOVE signal and FWD/BWD signal are set, and this time BWD (reverse)
Move the tape in the direction. The subsequent operations repeat what has been described above.

The operations of the reel motor control section 10 and the head position control section 11 when a read command is received from a host device are substantially the same as in the case of a write command. In this case, the difference from the write operation is that the data read from the read head is amplified by the read amplifier 13, decoded by the decoder 6, stored in the data buffer 2, and transferred to the interface circuit 1. The point is that the data is transferred to the higher-level device via the . The decoder 6 sends the read data to the error correction circuit 7b for checking. The error correction circuit 7b adds the
If an error exists due to the ECC code, it is corrected and the corrected correct data is stored in the data buffer 2. Like a 2-bit error
If correction is impossible due to the ECC code, this fact is reported to the control circuit 9.

Next, an example of an access method when a central processing unit uses the magnetic tape of the present invention as a library file using management information recorded in such a directory area is shown in FIGS. This will be explained with reference to FIGS. 6, 7, 9, and 10. FIG. 9 is a flowchart showing an execution format when a magnetic tape in this embodiment is used as a library file. Further, FIG. 10 is a diagram showing the overall system configuration.
In FIG. 10, 100 is the main memory, 100'
is a directory area provided in main memory, 10
1 is the CPU, 102 and 103 are channels, 104
105 is a magnetic tape device, and 105 is a magnetic disk device.

The CPU 101 issues a READ DIRECTORY command to the magnetic tape device 104. This reads the management information of all the directory sections of the magnetic tape M9 and stores it in the main memory 100 of the CPU 101.
This is an instruction for loading the file into the directory area 100' or the magnetic disk 106.

First, the magnetic tape M9 is rewound to the BOT mark position under the control of the control circuit 9 and the reel motor control section 10.

A control circuit 9 and a head position control unit 11 set the read/write head to track 1 (first track).
Positioned under the control of

Set track number i to 1.

The tacho pulse counters 29 and 30 are set to values corresponding to the recording length of the directory area.

P ₁ by tacho pulse counter 29, 30
Once the position is detected, the data block (directory portion of the track group shown in FIG. 5) is read out.

Transfer the read directory part to the directory area of main memory.

Check whether the gap (no signal area) lasted long. If Yes, the process ends and the process jumps to completion of creating the main memory directory area.
If No, perform processing.

Check whether or not a carry appears from tacho pulse counters 29 and 30. If Yes, perform the process, and if No, return to the process. In addition,
The appearance of a carry on the tacho pulse counters 29 and 30 indicates that the head has reached the head position change point.

The POSITION signal output from the head position control section 11 is used to check whether track number i is equal to j (last track number). If Yes, exit and jump to the next page. If No, perform processing.

Position the read/write head on track i+1, and let i be i+1.

Move on to processing by reversing the tape movement direction,
As the tape moving direction is reversed, another magnetic head is selected. Then move on to processing.

Next, in order to write management information as shown in Figure 5 into the directory section, WRITE
There is a command called DIRECTORY. When this command is received, a write process is performed instead of the process shown in FIG. 9, and the written data is immediately read out and the write data is checked by the check circuit 7a, but the process is not executed. Other reasons are substantially the same as in FIG. 9.

The CPU 101 refers to the management information read into the directory 100' and checks whether the desired file exists.

If the desired file exists on the magnetic tape, the CPU 101 performs a LOAD function to position the read/write head at the starting point of the track where the beginning of the desired file is recorded.
A TRACK command is sent to the magnetic tape device 104.

The CPU 101 sends a SERCH FILE that has management information read from the directory area 100', that is, a tape mark serial number and distance information from the beginning of the tape to the beginning of a desired file (tachopulse counter value and tape reel winding amount) as parameters. A command is sent to the magnetic tape device 104.

Magnetic tape unit 104 sets this parameter in tacho pulse counters 29,30.

The magnetic tape device 104 drives the magnetic tape at high speed and positions the magnetic tape from the beginning of the tape to the head of a desired file based on distance information, tape mark serial numbers, and the like. As explained in FIG.
The control circuit 9 performs this based on the output value of . The control circuit 9 performs the above operation until the values of the tacho pulse counters 29 and 30 match the tape movement amount given by the management information transferred from the CPU 101.

When the values of the tacho pulse counters 29 and 30 match the tape movement amount according to the management information, the operation of the reel motors 16 and 17 is stopped.

In the manner described above, the magnetic tape is positioned at the beginning of the desired file information, and the file information is read out. The directory section is still updated in conjunction with updating the file information recorded on the magnetic tape 104, but this is done in the following manner. After updating the file information on the magnetic tape 104,
The CPU 101 updates necessary parts of all the management information recorded in the directory area 100' of the main memory 100 or the magnetic disk 106,
Issue the WRITE DIRECTORY command to write all updated management information to the directory section of the magnetic tape.

〔Effect of the invention〕

As is clear from the above description, the present invention has the following effects.

(b) By giving the recording position of file information as information from the reference position, even when recording file information in the longitudinal direction of the track, it is possible to position the target file information at high speed, and magnetic It becomes possible to use a tape device as a library file (b) It is possible to use a particularly low-priced serpentine magnetic tape device as a library file; What the system can provide (c) Since file information is recorded for each track group, error recovery can be performed without affecting other file information unlike conventional magnetic tape devices. This can be done for each group, simplifying error recovery (d) It is possible to update each track group (e) Since each track group has a directory section, the directory area can be simplified and the media It is possible to achieve remarkable effects such as being able to use the capacity effectively.

[Brief explanation of the drawing]

Fig. 1 shows an example of a serpentine magnetic tape device, Fig. 2 shows an example of a read/write head, and Fig. 3 shows the recording format of management information and data on a magnetic tape according to the present invention. Figure 4 is a diagram showing the recording format of data in the track group of the data area, Figure 5 is a diagram explaining management information recorded in the directory section, and Figure 6 is the configuration of the reel motor control section. Figure 7 is a block diagram of the head position control section and light amplifier, and Figure 8 is a block diagram of the head position control section and light amplifier.
Figure 9 shows the execution format of the WRITE command.
10 is a diagram showing the overall system configuration, and FIG. 11 is a diagram illustrating the data recording format of a magnetic tape in a conventional serpentine magnetic tape device. DESCRIPTION OF SYMBOLS 1...Interface circuit, 2...Data buffer, 3...Command decoding section, 4...Format generation section, 5...Encoder, 6...Decoder, 7...Error detection section, 8a...Status retention part, 8b... sense data holding part, 9... control circuit, 10... reel motor control part, 11...
...Head position control unit, 12...Light amplifier,
14... Supply reel, 15... Take-up reel, 16
and 17... reel motor, 18... read/write head, 19... head moving mechanism, R... read head gap, W... write head gap,
E... Erasing head gap, T ₁ or T ₂ ...
Track, P ₁ ... Directory start point, P ₂ ... Track 1 data start point, BOT ... Tape start point,
EOT...end of tape, MT...magnetic tape.

Claims (1)

[Scope of Claims] 1. In a serpentine magnetic tape device in which a plurality of pieces of file information are sequentially recorded in the longitudinal direction of a magnetic tape in units of file information, which is a set of a series of data, the magnetic tape has a directory area and data. The file information is recorded in the data area, and at least the file name, the number of the track where the beginning of the file information is recorded, and the reference position on the magnetic tape are used to record the file information in the data area. A recording method for a magnetic tape device, characterized in that distance information to an information recording position is recorded in the directory area. 2. The data area is divided into a plurality of track groups, each file information is recorded so as not to span two track groups, and the management information is recorded for each track group. A recording method for a magnetic tape device according to claim 1. 3 A plurality of pieces of file information are recorded in the data area of a magnetic tape in the unit of file information, which is a collection of a series of data, and at least the file name and the number of the track in which the beginning of the file information is recorded as management information for the file information. and a serpentine magnetic tape device in which distance information from a reference position on the magnetic tape to a recording position of the file information is recorded in a directory area of the magnetic tape, when a host device accesses the magnetic tape, the information in the directory area is recorded. reading the management information and creating a management table; the higher-level device refers to the management table and sends the management information of desired file information to the magnetic tape device; the magnetic tape device reads the management information based on the management information; An access method for a magnetic tape device, comprising positioning the magnetic tape at a recording position of desired file information.