JPH0440766B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention The present invention relates to a magnetic tape device of a type in which a tape is driven by two reel motors, and more specifically, in such a magnetic tape device, a block error occurs. Regarding the processing method when

Prior Art In a magnetic tape device that drives the tape by two reel motors, due to the lack of a tape buffer mechanism, when a block is processed, the block is temporarily stopped and then the tape is run in the opposite direction. , a method is adopted in which the head is positioned sufficiently in front of the block and the tape is stopped.

By the way, in conventional magnetic tape devices of this type, even when an error block occurs, the tape is stopped by performing the same operation as when the block processing has been normally completed, positioning the head at the same position. ing. Then, reprocessing of an error block is executed in the same procedure as normal processing after repositioning the tape to the tape stop position at the start of processing of the error block. As a result, the reprocessing time for error blocks is long, blocks are likely to shift due to tape reciprocation, and error blocks due to unrecoverable causes such as tape defects are needlessly retried. .

OBJECTS OF THE INVENTION An object of the present invention is to provide a block error handling method for realizing a magnetic tape device that eliminates the above-mentioned drawbacks of conventional magnetic tape devices.

General Description of the Invention According to the present invention, when the processing of a certain block ends with an error, the head is positioned at the first position ahead of the error block, the tape is stopped, and the tape is stopped at the first position ahead of the error block. First information regarding the distance from the first position is stored. Thereafter, when receiving a block space command for reprocessing the error block, the tape is run in the opposite direction and the head is positioned at a second position before the error block based on the first information. to stop the tape and store second information regarding the distance between the error block and the second location. Therefore, instead of sending the tape backwards as in the past, it is possible to immediately send the tape forward, check the position relative to the error block based on the second information, and execute reprocessing. It is no longer necessary to move the tape back and forth as in the above, and reprocessing time can be shortened, and at the same time block misalignment can be reliably prevented.

Further, according to the present invention, while the tape is running in reverse according to the space block command, it is checked based on the first information whether the error block and the immediately preceding gap are recognized at their expected positions;
If it is not recognized normally, reprocessing for the error block is stopped. This makes it possible to avoid unnecessary repetition of reprocessing for blocks that have caused errors due to tape defects or the like.

Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

A schematic configuration diagram of a tape running system of a magnetic tape device according to the present invention is shown in FIG. 1, and a functional block diagram is shown in FIG. 2.

First, the tape running system will be explained. In FIG. 1, there are a machine reel 1 and a file reel 2 which are rotationally driven by separate reel motors (not shown). When the tape 8 is running in the forward direction, it is unwound from the file reel 2, and the tape tension detection mechanism 7, tape guide 5, head 3 (including a read head, write head, and erase head as shown in FIG. 2), and tape guide 4. Tape speed detection mechanism 6
, and is wound onto machine reel 1. When running in the reverse direction, the tape 8 is attached to the machine reel 1.
from there to file reel 2. The tape speed detection mechanism 6 is provided with a tachometer that rotates in synchronization with the tape 8 and sends out tacho pulses at a cycle corresponding to the tape running speed.

Next, each functional block shown in FIG. 2 will be explained.

It is connected to a host device 51 via an interface 52. The write data transferred from the host device 51 is taken into the write data control circuit 53 through the interface 52, and the corresponding write signal is sent to the write head 54 via the write amplifier 50.
and written on tape 8 (FIG. 1).
55 is an erase head, which is also connected to the write amplifier 5.
0.

56 is a read head. The data output from the read amplifier 57 which receives the output signal as input undergoes error correction processing in the error correction circuit 58, and then is transferred from the read data control circuit 59 to the host device 51 via the interface. During read processing and during read-after-write operations during write processing, the read data control circuit 59 identifies blocks containing errors that cannot be corrected by the error correction circuit 58, and when such an error block is detected, it notifies the block to that effect. The information is reported to the host device 51 and the servo control circuit 60. Further, recognition of blocks and inter-block gaps (IBGs) is also performed by the read data control circuit 59, and the recognition results are also supplied to the servo control circuit 60.

The servo control circuit 60 controls a reel motor 6 for a machine reel and a file reel through a machine reel drive circuit 61 and a file reel drive circuit 62.
3,64 drive control is performed. The servo control circuit 60 receives the tacho pulse from the tachometer described above via the sensor circuit 66, and has built-in counters (1) and (2) that count up or down based on the tacho pulse.

As shown by the broken line in the figure, in this example,
Some of the functions of the read data control circuit 59 and the write data control circuit 53, and the servo control circuit 60
adopts a microprogram control method,
A schematic flowchart of the microprogram is shown in FIG. 3 (however, only the parts related to the write process are shown).

FIG. 4 is a diagram illustrating blocks on the tape and the temporal changes in the moving speed of the tape and the relative position with respect to the head during writing processing for block D. Before the start of processing, the tape is stopped with the head positioned at position A in the figure (the stop position after the processing of the previous block C is normally completed).

The operation of block D during write processing will be described below with reference to FIGS. 3 and 4.

When a data write processing command is received from the host device 51 (step (1)), the magnetic tape device is activated and the tape is driven to run in the forward direction under the control of the servo control circuit 60 (step (2)).

The end of block C is the read data control circuit 59
When this is recognized, the counter (1) in the servo control circuit 60 starts counting up using the tacho pulse. The value of this counter (1) indicates the distance from block C, and when the distance reaches a value corresponding to the length of the interblock gap (IBG),
After confirming that the IBG is secured (step (3)), the servo control circuit 60 checks the tape running speed based on the period of the tacho pulse (step (4)).

If the tape speed is normal, the servo control circuit 6
After the counter within 0 is cleared, it starts counting up with the tacho pulse, and at the same time a data transfer request is issued to the host device 51 (step (7)). The data to be transferred is sequentially written onto the tape by the write head 54 under the control of the write data control circuit 53, and the data is immediately read out by the read head 56 (that is, read-after-write is executed). During this write operation, a check for completion of data transfer (step (8)) is performed, and when the data transfer is completed, the servo control circuit 60 checks the tape running speed from the period of the tacho pulse (step (8)).
(9)). Almost at the same time, the data read control circuit 59 checks whether the write process of block D has been completed normally (step (10)).

If the processing of block D ends normally, counters (1) and (2) in the servo control circuit 60 are once cleared and then start counting up using tacho pulses. The value of the counter (1) in the servo control circuit 60 is
It is checked whether the value corresponding to the IBG has been reached, and it is monitored whether a processing command for the next block arrives within the interval (command re-indication distance) shown by the symbol B in FIG. 4 (step (12)). If no data processing command is received in this section, the servo control circuit 60 executes a stop operation (step (13)).

That is, after the tape has run a certain distance indicated by the symbol C in FIG. 4, deceleration is started, the head is positioned, and the tape is stopped. At this time, the distance from block D to position N is stored in counter (1). Next, the tape is run in the reverse direction, and after the tape has traveled a certain distance indicated by the symbol 0 from the point when the value of the counter (1) reaches zero, that is, the head is located at the end of block D, the tape starts to decelerate. death,
Position the head at position T and stop the tape.

The above is the operation when the processing of block D is normally completed, and is the same as in the prior art. In addition, step
If the tape speed is determined to be abnormal in (4), the magnetic tape device is stopped. Further, if a data processing command is accepted in step (12), processing for the next block is continued (the same processing as from step (7) onward is repeated).

Now, when it is determined in step (10) that block D has ended due to an error, the flow of processing switches to step (15) and subsequent steps.

That is, the counter (1) in the servo control circuit 60
After clearing, restart the count-up (step (15)). Here, counter (2) is not cleared. As in the case of normal termination, after securing the IBG and traveling a certain distance C, the servo control circuit 60 starts decelerating the tape, positions the head at position N, and stops the tape (step (16)). In this state,
It waits for a space block command for reprocessing block D (step (17)). counter(1)
The values of and (2) indicate the distance from the end and start end of block D to position N, respectively.

When the space block command is transmitted from the host device 51, the servo control circuit 60 starts driving the tape in the reverse direction (step (18)). At the same time, countdown (by tacho pulse) of counters (1) and (2) is started (step (19)).

A zero check is performed on the value of the counter (1) (step (20)), and when the value becomes zero, that is, when the head reaches the end of block D, the read data control circuit 59 checks whether block D is correctly recognized. (Step (21)). That is, it is checked whether the block D is detected at the desired position or whether the block D is continuous over its original length without being interrupted by gaps or the like.
However, the connectivity check range of block D is
This is from the rear end of block D until the next step (22) is satisfied.

When the value of the counter (2) changes from 8 to 0 (step (22)), the read data control circuit 59 checks whether the IBG is correctly recognized (step (23)). If IBG is not recognized, counter (2)
Repeat step (23) until the value of becomes zero (step (24)). In this way, when the IBG is recognized at the desired position, counters (1) and (2) are cleared and the countdown is restarted. If IBG is not detected even when the counter (2) reaches zero, it is checked whether IBG is detected until the counter (2) counts down to a predetermined negative value (step (25)). If an IBG is detected in this step (25), the process proceeds to step (26), but if no IBG is still detected, the process proceeds to step (31) and the apparatus stops processing.

After step (26), it is checked whether the counter (2) has counted down to a predetermined negative value (step (27)), and when that value is reached, the tape starts to decelerate after traveling a certain distance, and when it reaches the vicinity of position T. Position the head and stop the tape (step (28)).
At this time, the values of counters (1) and (2) are
The distance from approximately the tip of the head to the stop position of the head is shown.

Thereafter, when a reprocessing command is transmitted, the tape is driven to run in the forward direction, and block D is reprocessed based on the value of the counter (1).

If block D is not recognized in step (21), the system waits until the counter 2 reaches a predetermined negative value (step (30)), and then stops the processing (step (31)).

The above explanation was for the data write process, but the same applies to the data read process, so the explanation will be omitted.

Effects of the Invention As described in detail above, according to the present invention, when block processing ends with an error, control is switched between when it ends normally and when the process ends normally, and the error block can be reprocessed without wasteful reciprocating of the tape. It is possible to efficiently execute the process, and also prevent block misalignment. Also, by checking whether the error block and the previous gap are recognized in their expected positions while the tape is being fed in the reverse direction using the block space command, error blocks due to unrecoverable causes are avoided. Reprocessing can be stopped.

Thus, according to the present invention, highly reliable
A magnetic tape device with excellent processing efficiency can be realized, and its effects are significant.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining one embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram of a tape running system of a magnetic tape device, and FIG. 2 is a functional block diagram of the magnetic tape device. , FIG. 3 is a schematic flowchart of a microprogram for explaining the data write processing operation, and FIG. 4 is a diagram showing blocks on the tape and how the tape runs. 1... Machine reel, 2... File reel,
3...Head, 5...Tape speed detection mechanism, 8...
...Tape, 53...Write data control circuit, 54
...Write head, 55...Erase head, 56...
...Reading head, 59...Reading data control circuit, 60... Servo control circuit, 63, 64... Reel motor.

Claims (1)

[Scope of Claims] 1. In a magnetic tape device of the type in which the tape is run by two reel motors, when processing of a certain block ends with an error, the head is positioned at the first position beyond the error block. to stop the tape, and to record a first position related to the distance from the end of the error block to the first position.
and second information regarding the distance from the tip of the error block to the first position, and upon receiving a command to reprocess the error block, reverse the tape. The tape is run, the end of the error block is detected based on the first information, the gap between the blocks in front of the error block is detected based on the second information, and then the tape is After traveling a certain distance, deceleration is started, the head is positioned at a second position in front of the error block, and the head is stopped. A block error handling method characterized by storing information and reprocessing the error block based on the third information. 2. When the end of the error block and the gap between blocks are not detected based on the first information and the second information while the tape is running in the reverse direction, reprocessing for the error block is stopped. A block error processing method according to claim 1, characterized in that: