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Improved Direct Access Storage Device Save/Restore Testing Method

IP.com Disclosure Number: IPCOM000039464D
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Crowley, TR: AUTHOR [+2]

Abstract

Ensuring the accuracy of the operation which saves the data from a DASD (direct access storage device) unit onto removable media (magnetic tape) while preserving both the data and the created error conditions on the DASD unit is accomplished by the use of code which simulates the data restore operation. The sequence of steps used during the Unit Test phase of the DASD restore code is as follows: 1.'Condition' the DASD unit for the Save operation as follows: a. Sequence the DASD unit (write a unique sequence number to each sector on the DASD unit). b. Create the error conditions on the DASD unit (datachecks, on-track alternates, off-track alternates, etc.). 2.Execute the Save code to read the data from the DASD unit and write the data to tape. a. Read sectors of data from the DASD.

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Improved Direct Access Storage Device Save/Restore Testing Method

Ensuring the accuracy of the operation which saves the data from a DASD (direct access storage device) unit onto removable media (magnetic tape) while preserving both the data and the created error conditions on the DASD unit is accomplished by the use of code which simulates the data restore operation. The sequence of steps used during the Unit Test phase of the DASD restore code is as follows:
1.'Condition' the DASD unit for the Save operation as follows:

a. Sequence the DASD unit (write a unique sequence number to

each sector on the DASD unit).

b. Create the error conditions on the DASD unit (datachecks,

on-track alternates, off-track alternates, etc.). 2.Execute the Save code to read the data from the DASD unit and write the data to tape.

a. Read sectors of data from the DASD.

b. Compress the data in the sectors.

c. Write the compressed data to tape. 3.Execute the code which simulates the function of the code which would normally read the data from the tape and restore it to the

DASD unit. The simulator code does not actually write any data to

the DASD unit. The code does the following, as indicated in the

flowchart of the operation:

a. Read a block of tape data.

b. Decompress the data in the block.

c. Compare the decompressed data to ensure the sequence numbers

created for sectors in step 1 are present in the correct order. Using this testing technique, the sequence numbers on the DASD units a...