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Recalling Data in a Distributed Processing System

IP.com Disclosure Number: IPCOM000046313D
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Kamionka, HE: AUTHOR

Abstract

A multihost system includes programming controls that migrate aged data from the primary external data storage DASD (direct-access storage device) to magnetic recording tape for long-term storage. When any of the hosts need data that has been migrated to tape, a recall operation is instituted. Each host institutes its own recall operation independent of the other hosts. When a first host has a mounted tape volume for recall or other purposes and another host decides it needs a data set which is recorded on that mounted tape volume, the other host examines a common data set in DASD to see if the desired tape volume is mounted in the multihost environment. If it is mounted, the other host sends a request to the host mounting the tape to transfer the data set desired to be recalled to a shared DASD.

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Recalling Data in a Distributed Processing System

A multihost system includes programming controls that migrate aged data from the primary external data storage DASD (direct-access storage device) to magnetic recording tape for long-term storage. When any of the hosts need data that has been migrated to tape, a recall operation is instituted. Each host institutes its own recall operation independent of the other hosts. When a first host has a mounted tape volume for recall or other purposes and another host decides it needs a data set which is recorded on that mounted tape volume, the other host examines a common data set in DASD to see if the desired tape volume is mounted in the multihost environment. If it is mounted, the other host sends a request to the host mounting the tape to transfer the data set desired to be recalled to a shared DASD. A single stage of data from tape to the shared DASD makes the data available to the other host without manual intervention,
i.e., no tape reel mount.

Hosts 1 and 2 are a part of a multihost environment. The two hosts share a DASD and have independent tape drive units 1 and 2. As shown, tape volume VOLSER XX is mounted to host 1, while tape volume VOLSER AB is mounted to host 2. Each of the hosts, upon having the respective tape volumes mounted, records the mounting in a common data set (CDS) within the shared DASD. As shown, CDS shows that VOLSER XX is mounted to host 1 while VOLSER AB is mounted to host 2.

When host 2 ne...