Browse Prior Art Database

Preserving Tape Mounts

IP.com Disclosure Number: IPCOM000046737D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Bittihoffer, JR: AUTHOR [+2]

Abstract

In the batch sequential processing of data sets that were migrated to tape volumes from other data storage apparatus, the mount status of the currently mounted tape volume can be preserved by providing a multisecond delay after completing an access to one data set and demounting the tape volume. This delay allows for the addition of more recall requests that will use the same tape volume while preserving the tape mount status; hence gives quick access to another data set. In batch processing, similarly aged data sets would have been migrated to tape at about the same time; this means there is a strong likelihood that cyclically processed data sets will be on the same tape volume. This procedure is particularly advantageous when using sequentially accessible media.

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Preserving Tape Mounts

In the batch sequential processing of data sets that were migrated to tape volumes from other data storage apparatus, the mount status of the currently mounted tape volume can be preserved by providing a multisecond delay after completing an access to one data set and demounting the tape volume. This delay allows for the addition of more recall requests that will use the same tape volume while preserving the tape mount status; hence gives quick access to another data set. In batch processing, similarly aged data sets would have been migrated to tape at about the same time; this means there is a strong likelihood that cyclically processed data sets will be on the same tape volume. This procedure is particularly advantageous when using sequentially accessible media. A programmed digital computer receives a request for data that has been migrated to magnetic tape. Restoration of the data on the tape to DASD for use by the requestor is termed "recall". The computer begins recall by having the tape mounted on a suitable magnetic tape unit coupled to the computer. Once the tape is mounted, the data set (DS) recorded on that tape is recalled, i.e., transferred from tape to other data storage units, such as direct-access storage devices DASDs (not shown). The digital computer also keeps a queue of work to be done. After recall of the data set DS from the tape, the work queue is scanned to determine whether or not additional recalls from the mounted...