JPS63136302A - Retrial control system for magnetic tape controller - Google Patents

Abstract

PURPOSE:To confirm the normality of reversing operation of one record by stopping the succeeding processing, if the difference of the running distance between both forward and backward directions in one record is not within the allowable value in the reversing operation with respect to a write error and reporting it to a host device. CONSTITUTION:A data is written in a magnetic tape medium during the write and if a write error takes place, the running distance from the start of write till the end is measured. Then the running distance for the forward or reverse operation of one record is measured to confirm whether or not the difference between both forward and reverse running distances of one record is within the permissible value is confirmed. If not within the permissible value, either forward or reversing is applied by one record again depending on the difference, the result is compared again whether or not it is within the permissible value for one record and if not within the permissible value, the succeeding processing is stopped and it is reported immediately to the host device. Thus, the normality of reversing for one record is confirmed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic tape control device used in an information processing system, and particularly relates to a retry control method in the event of an error in a write operation to a magnetic tape medium. be.

[Conventional technology]

Conventionally, when a write operation error occurs during a write operation to a magnetic tape medium, the magnetic tape control device either causes a fatal failure for the number of times instructed by the software, or backs up one record until it completes normally. Although the erase operation and rewrite operation were performed, it was not confirmed whether the backward operation for one record was correctly executed for one record.

[Problem that the invention seeks to solve]

In the conventional method described above, since it is not checked whether the backward movement command to move back the record in which the write operation error has occurred is correctly performed by one record, the record in which the write operation error has occurred is mistakenly moved back. There was a problem in that even if the user went back to the previous record, the error could not be detected, and the erase operation and rewrite operation were performed to delete one normal record.

[Means for solving problems]

The retry control method of the magnetic tape control device of the present invention includes a first method of measuring the travel distance from the start of the write operation to the end of the write operation when a write operation error occurs during a write operation on a magnetic tape medium. a measuring means, a second measuring means for measuring the traveling distance when performing forward or backward movement of one record, and a second measuring means for measuring the traveling distance when performing forward or backward movement of one record, and a second measuring means for measuring the distance traveled when performing forward or backward movement of one record; A means for checking whether the difference in distance is within the tolerance value, and if it is not within the tolerance value, perform either forward movement or backward movement by one record again from the difference value to ensure that the difference is within the tolerance value. The apparatus is equipped with a means for comparing whether or not the data is present, and if it is not found, stopping the subsequent processing and immediately reporting the fact to the higher-level device.

[Effect]

In the present invention, the normality of one record backward operation is confirmed by the write operation retry process of the magnetic tape control device.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

The figure is a flowchart showing processing of a retry control method of a magnetic tape control device to which the present invention is applied.

In this flowchart showing the processing of an embodiment of the present invention, after receiving a write operation instruction from the host device to the magnetic tape control device and performing the write operation, step 100 is first performed.
Checks whether there is a write operation error, and if there is no write operation error, the process goes to normal end processing. If there is a write operation error, the distance traveled from the start of the write operation to the end of the write operation is registered in the storage area A in step 101.

Next, in step 102, a one-record backward operation is performed to rewrite the record with the write operation error. At this time, in step 103, the distance traveled from the start to the end of the backward motion for one record is registered in the storage area B. After that, it is compared whether the difference between storage area A and storage area B registered in step 104 is within the tolerance value, and if it is within the tolerance value, step 1
In step 05, the erase operation is performed and the process proceeds to the rewrite operation. On the other hand, if the difference between storage area A and storage area B is not within the allowable value, the content of storage area B is compared with the storage area person in step 106, and if the difference between storage area A and storage area B is larger, step 107 is performed. A one-record backward movement is performed, and in step 108, the distance traveled when the one-record backward movement is performed is added to the storage area CK.

Thereafter, in step 10i9, the difference between storage area B and storage area C is registered in storage area E, and in step 110, it is compared whether the difference between storage area A and storage area E is within a tolerance value. If it is within the allowable value, the process jumps to step 105; if it is not within the allowable value, it is determined that the positioning is incorrect, and the process goes to abnormal termination processing to cancel the retry process and notify that fact. Report to the higher-level device. Also, in step 106, storage area A and storage area B are
The contents of storage area B are compared, and if storage area B is larger, advance operation is performed by one record in step 111, and step 1
In step 12, the distance traveled when one record forward movement is performed is registered in the storage area D.

After that, in step 113, storage area B and storage area D are
and is registered in the storage area E, and the process jumps to step 110.

As is clear from the foregoing, step 102 in the flowchart shown in this figure constitutes a means for measuring the traveling distance when one record of forward or backward movement is performed, and step 104 constitutes means for measuring the distance traveled when performing one record of forward or backward movement, and step 104 constitutes a means for measuring the distance traveled when one record of forward or backward movement is performed. Constructs means for checking whether the difference between the traveling distances of both the forward and backward travels of the one record is within an allowable value when performing a backward movement, and also includes steps 106 and 107.
...113, if it is not within the above tolerance, either move forward or backward one record again from the above difference and compare whether it is within the tolerance, and if it is not within the tolerance, cancel the subsequent processing. This constitutes means for reporting this to the immediately higher-level device. The write operation in this flowchart includes means for measuring the travel distance from the start of the write operation to the end of the write operation when a write operation error occurs during the write operation on the magnetic tape medium. Contains.

In the above embodiment, the case where the normality of the backward movement after a write operation error is confirmed based on the mileage is explained as an example, but the present invention is not limited to this, and the present invention is not limited to this. A counter or clock could be used instead.

〔Effect of the invention〕

As explained above, according to the present invention, by confirming the normality of one record backward operation in the write operation retry process of the magnetic tape control device, IT processing that accidentally destroys a normal record The practical effect is extremely large, since it is possible to continue the process and prevent the problem of finding out later that a record is missing.

[Brief explanation of the drawing]

The figure is a flowchart showing processing of a write operation retry control method of a magnetic tape control device to which the present invention is applied. 100-113--l Processing steps of retry control method.

Claims (1)

[Claims] A first measuring means for measuring the travel distance from the start of the write operation to the end of the operation when a write operation error occurs during a write operation on a magnetic tape medium, and a first measuring means for performing a forward or backward operation of one record. a second measuring means for measuring the actual traveling distance; and a second measuring means for measuring the traveling distance at the time of writing, and determining whether or not the difference between the traveling distance for both forward and backward traveling of the one record is within an allowable value when performing a backward operation in response to a write operation error. If the difference is not within the allowable value, perform one record forward or backward operation again from the difference and compare whether it is within the allowable value, and if it is not within the allowable value, cancel the subsequent processing. 1. A retry control method for a magnetic tape control device, comprising means for immediately reporting the same to a higher-level device.