JPH0721945B2 - Data error processing method in magnetic tape device - Google Patents

Description

The present invention relates to a data error processing method in a magnetic tape device, which aims to improve the recovery rate of data errors that occur during recording / reproduction of data on a magnetic tape medium. A magnetic tape device for recording / reproducing information on / from a medium by a magnetic head, wherein when a data error is detected during recording / reproducing of data on a magnetic tape medium, the magnetic head is moved in the width direction of the magnetic tape. After reciprocating a plurality of times, the structure is returned to the original position, and then the retry process for the data error is performed.

[Field of Use of Invention]

The present invention relates to a magnetic tape device used as an external storage device of an information processing system, and more particularly to a method of processing a data error that occurs during recording / reproduction of data on a magnetic tape medium.

The magnetic tape device drives a magnetic tape medium between a pair of reels at a predetermined speed, and a magnetic head faces the tape medium to record / reproduce data.

The magnetic tape medium is stored in a cartridge or the like in a state of being wound on a reel and used as a portable medium.

In such a magnetic tape device, it is desired to be able to sufficiently deal with a data error caused by dust in particular.

[Prior art]

The conventional data error processing methods of the magnetic tape device are roughly classified into data recording and reproduction on the magnetic tape medium.

At the time of recording data on the magnetic tape medium, the data recorded on the magnetic tape medium is reproduced by a reproducing magnetic head provided in parallel with the recording magnetic head, and as a result, it is determined whether or not there is an error.

Then, if an error is detected at this time, rewriting of the data referred to as retry is performed.

This rewriting of data allows a predetermined number of retries.

On the other hand, when reproducing data from the magnetic tape medium, it is judged whether there is an error in the reproduced data as in the case of recording the data, and if an error is found, it is retried as in the case of recording. Some rereads are allowed a predetermined number of times.

As described above, the conventional processing for a data error has been performed in the form of a retry of recording / reproducing data to / from a magnetic tape medium.

On the other hand, recently, a method described in JP-A-60-59572 has been proposed as a data error processing.

This method is limited to the case of reproducing information from a magnetic tape medium, but if a data error is detected during the reproduction of data, retry is performed in the same manner as the conventional method described above. When the data error is not eliminated even by the result of the retry, the magnetic tape device is offset by a predetermined distance in the width direction of the magnetic tape medium and the retry is performed.

This method is adopted in a magnetic tape device of a recording system generally called a serpentine system.

This serpentine type magnetic tape device has a moving mechanism for moving the magnetic head in the width direction of the magnetic tape, records / reproduces data in units of one or several tracks in the longitudinal direction of the magnetic tape medium, and When the end of the tape medium is reached, the magnetic head is moved in the width direction of the magnetic tape medium to select a track, and this time the magnetic tape medium is run from the end of the magnetic tape medium toward the beginning of the magnetic tape medium. Information is recorded and reproduced on the magnetic tape medium by recording information and repeating this.

Since such a magnetic tape device has a mechanism for accessing the magnetic head in the width direction of the magnetic tape medium, an error in the movement of the head may cause an error. It was done.

[Problems to be solved by the invention]

As described above, none of the conventional data error processing methods in the magnetic tape device is sufficient in the case of a data error caused by dust.

That is, the dust attached to the magnetic head can be removed to some extent by moving the magnetic tape medium in the longitudinal direction of the magnetic tape medium during the retry.

However, dust that originally adhered when running in the longitudinal direction of the magnetic tape medium cannot be sufficiently removed only by moving the tape in the longitudinal direction of the magnetic tape medium, and data errors caused by dust can be sufficiently relieved. There was a problem of not having.

It is an object of the present invention to solve the above-mentioned problems, and particularly to improve the recovery rate for data errors caused by dust adhesion.

[Means for solving problems]

In order to achieve the above object, a data error processing method in a magnetic tape device according to the present invention is: When a data error is detected during recording / reproducing of data to / from a magnetic tape medium, the magnetic head in the width direction of the magnetic tape. Is reciprocated a plurality of times and then positioned at a predetermined position, after which retry processing for the data error is performed.

[Action]

That is, according to the present invention, when a data error is detected during data recording / reproduction with respect to a magnetic tape medium, the magnetic head is reciprocated a plurality of times in the width direction of the magnetic tape medium, thereby adhering to the magnetic head in particular. The dust is effectively removed, and the retry operation is performed.

That is, in the present invention, attention is paid to the fact that dust adheres when the magnetic tape medium is running in the longitudinal direction, and the dust is effectively removed by moving the magnetic head in the width direction of the magnetic tape. With this configuration, it becomes possible to recover a data error that could not be recovered by the conventional retry.

〔Example〕

FIG. 1 is a block diagram of an embodiment of a magnetic tape device for carrying out the present invention.

In the figure, 1 is a microprogram processor, 2 is a magnetic tape medium (hereinafter simply referred to as a magnetic tape), 3 and 4 are reels, 5 and 6 are reel drive motors, 7 is a magnetic head, 8 is a head drive mechanism, and 9 is a head drive mechanism. Is a data recording circuit, 10 is a data reproducing circuit, 11 is a data inspection circuit, and 12 is a retry counter.

The micro program processing device 1 operates according to a command from a host device such as a channel device (not shown) and controls the drive of the entire magnetic tape device. The processor and the program for operating the processor are stored inside. There is.

The magnetic tape 2 is driven and controlled by motors 5 and 6 that drive reels 3 and 4, and runs at a predetermined speed.

The magnetic head 7 is placed in a substantially sliding contact state with respect to the magnetic tape 2 to record / record data on / from the magnetic tape 2.
Play.

The magnetic head 7 is connected to the data recording circuit 9 and the data reproducing circuit 10.

The data recording circuit 9 is composed of a circuit that modulates the binary data sent from the host device into a signal for recording on the magnetic tape 2 and creates a recording current for driving the magnetic head. .

The data reproducing circuit 10 demodulates the data reproduced by the magnetic head 7 from the magnetic tape 2 and converts it into binary data.

The data inspection circuit 11 detects the data error of the data reproduced from the magnetic tape 2 by using the inspection code in the reproduced data.

In the case of a serpentine type magnetic tape device, the head moving mechanism 8 is used to move the magnetic head 7 in the longitudinal direction of the magnetic tape 2 to select a track and to perform the data error processing of the present invention. However, this structure will be described in detail in FIG.

FIG. 2 shows a detailed structure of the head moving mechanism 8 in FIG.

In the figure, the same symbols as in FIG. 1 indicate the same,
In the figure, 13 is a step motor, 14 is a feed screw, and 15
Indicate guides, respectively.

As shown in the figure, the magnetic head 7 is mounted on a head drive mechanism, and in order to drive the magnetic head in the width direction of the magnetic tape 2, the feed screw 14 is driven by a step motor.

The guide 15 is for guiding the movement of the magnetic head and preventing the head from falling.

The data error processing method of the present invention will be described with reference to FIGS. 1 and 2 with reference to FIG.

FIG. 3 is a processing flowchart of an embodiment of the data error recovery processing of the present invention.

Processing Steps When a data recording / reproducing command arrives from an upper channel device (not shown) in the magnetic tape device as shown in FIG. 1, the microprogram processing device 1 clears its own retry counter 12 to zero.

Processing step When the command from the host device is a recording command.

When a recording command is issued, the microprogram processing device 1 drives and controls the motors 5 and 6 to start the running of the magnetic tape 2, and transmits write data transferred from a channel device (not shown) via the data recording circuit 9. Magnetic head 7
Thus, the recording is started in a unit of one block, the data on the magnetic tape 2 after recording is read by the magnetic head 7, is input to the data reproducing circuit 10, and the binary data as a result of the demodulation is sent to the data inspection circuit 11.

When the command from the host device is a playback command.

When a reproducing command is issued, the microprogram processing device 1 controls the driving of the motors 5 and 6 to start the running of the magnetic tape 2 and reads the data from the magnetic tape 2 by the magnetic head 7 to the data reproducing circuit. After being demodulated to binary data to be sent, it is transferred to a higher-order channel device (not shown) and sent to the data inspection circuit 11.

Processing Step As a result of recording / reproducing data for one block in the above processing step, the microprogram control device 1 judges whether or not there is an error from the data inspection circuit 11, and if the data is normal, it is normally terminated by the upper channel device. And wait for the next instruction.

On the other hand, if there is an error, the error recovery process is started by the subsequent process in the next step.

Although details of the data inspection circuit 11 are omitted here, correction can be performed by performing an error recovery process when the data can be corrected by the inspection code even if there is an error due to the type of the inspection code during data reproduction. It may not move.

Normally, a check code for correcting 1-bit error and detecting 2-bit error is added to the data.

Processing step When an error is detected by the above processing step and the check code cannot correct or data is recorded, the error is retried, but it cannot be retried indefinitely until the error is recovered. For example, if the error is not recovered even after retrying about 15 times, it is necessary to make a retry out, and this is the step for making that determination.

Therefore, the micro program control device 1 has a retry counter 12 inside, and the retry counter 12
The value of 12 is referenced to determine whether to retry.

Therefore, in this step, it is determined whether or not the value of the retry counter 12 is the number of retries within the allowable range, and if the value exceeds the allowable range, retry-out processing described later is performed.

On the other hand, if the number of retries is within the allowable range, the process proceeds to the next step.

Processing Step When the number of retries is determined to be within the allowable range in the above processing step, it is determined in this processing step whether or not to perform the data error processing of the present invention.

This determination is made based on whether the number of retries is a predetermined number.

For example, when the data error processing of the present invention is performed when the number of retries is the eighth, the process proceeds to the processing step when the number of retries is the eighth, and proceeds to the processing step at other times.

Note that, in this example, the data error processing of the present invention is performed only when the number of retries is one, but when the number of retries is plural, for example, the number of retries is 2, 4, 8, 10 It may be performed at the time of.

It is also conceivable to perform the data error processing of the present invention from the time of the first retry, but in the case of a data error due to a factor other than the present invention and in the case of a data error due to dust adhering to the magnetic tape side. Since there are generally more cases, performing the data error processing of the present invention from the beginning is not a good idea considering the wear of the magnetic tape 2.

Therefore, this is usually done if the error is not resolved after multiple retries.

Processing Step The processing step is the data error processing of the present invention.

The processing here is to reciprocate the magnetic head 7 in the width direction of the magnetic tape 2.

That is, the head moving mechanism 8 is driven by the program control stored in the micro program controller 1, and the magnetic head 7 is reciprocated in the width direction of the magnetic tape 2 a plurality of times.

Specifically, as shown in FIG. 2, the step motor 13 is driven by several steps in the plus and minus directions from the initial operation value, and finally returned to the initial operation value.

By operating in this manner, the removal of dust attached to the magnetic head, in particular, is performed by the conventional magnetic tape 2 by simply retrying.
It is possible to effectively remove only for the movement in the longitudinal direction.

Processing Step In the processing step, the retry counter 12 provided in the microprogram controller 1 is incremented by 1 in preparation for the next retry operation.

Processing step In the processing step, to prepare for the retry operation,
The following operations are performed.

When recording data, backspace the magnetic tape 2,
The operation of positioning the magnetic head 7 at the head of the block recorded on the magnetic tape 2 in which the error has occurred is performed.

This is performed based on the search of the inter-block gap (IBG) on the magnetic tape 2 or the length of the block in which the data recorded on the magnetic tape 7 in which an error has occurred.

When recording data, if there is a scratch on the magnetic tape 2, recovery of the error cannot be expected even if it is re-recorded repeatedly at the same position. Therefore, the magnetic tape 2 is backspaced up to the beginning of the block where the error occurred. After that, it is necessary to erase the data for a predetermined length and then re-record the day block.

Also, when reproducing data, the magnetic tape 2 is backspaced so that the magnetic tape 2 is positioned at the beginning of the block to be reproduced by the same method as that used for recording.

Processing step The processing step records / records data when a predetermined number of retries is exceeded in the processing step.
Since the error at the time of reproduction cannot be recovered, it is reported to the upper channel position via the microprogram controller 1 that the error cannot be recovered.

〔effect〕

As described above, according to the present invention, in the retry when a data error occurs in the magnetic tape device, the dust adhering to the magnetic head can be removed by reciprocating the magnetic head a plurality of times in the width direction of the magnetic tape. Therefore, the recovery rate of data errors can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a magnetic tape device for carrying out the present invention. FIG. 2 shows a detailed structure of the head moving mechanism 8 in FIG. FIG. 3 is a processing flowchart of an embodiment of the data error recovery processing of the present invention. In the figure, 1 is a microprogram processor, 2 is a magnetic tape medium, 3 and 4 are reels, 5 and 6 are reel drive motors, 7 is a magnetic head, 8 is a head drive mechanism, 9 is a data recording circuit, and 10
Is a data reproducing circuit, 11 is a data inspection circuit, and 12 is a retry counter.

Claims (1)

[Claims] 1. A magnetic tape device for recording / reproducing information on / from a magnetic tape medium by a magnetic head, wherein when a data error is detected during recording / reproducing of data to / from the magnetic tape medium, A data error processing method in a magnetic tape device, comprising reciprocating the magnetic head a plurality of times in the width direction, returning the magnetic head to the original position, and then performing retry processing for the data error.