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Recalling Migrated Data Sets

IP.com Disclosure Number: IPCOM000041579D
Original Publication Date: 1984-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Kamionka, HE: AUTHOR

Abstract

In a multi-level peripheral data storage hierarchy, data sets that are active are kept in a fast access portion of the hierarchy. Data sets that are currently not being used are migrated to lower elements of the hierarchy using known replacement control techniques. After such migration, usage of the migrated data sets may be required. Accordingly, the volume serial number (VOLSER) of the volume which contains the data set is required by a job control module in a host processor connected to the hierarchy. The job control module requests an intercept module to locate the VOLSER volume storing the data set. The intercept module recognizes that the data set is migrated and indicates to the job control module that the "locate VOLSER request" cannot be satisfied.

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Recalling Migrated Data Sets

In a multi-level peripheral data storage hierarchy, data sets that are active are kept in a fast access portion of the hierarchy. Data sets that are currently not being used are migrated to lower elements of the hierarchy using known replacement control techniques. After such migration, usage of the migrated data sets may be required. Accordingly, the volume serial number (VOLSER) of the volume which contains the data set is required by a job control module in a host processor connected to the hierarchy. The job control module requests an intercept module to locate the VOLSER volume storing the data set. The intercept module recognizes that the data set is migrated and indicates to the job control module that the "locate VOLSER request" cannot be satisfied. Simultaneously, the intercept module makes a recall request to the hierarchy for the desired data set. As a result of the failing indication, an adumbrative indication, the job control module is free to process other requests. The failing request is sent to an exit to obtain the appropriate VOLSER information. The recall request, asynchronously initiated by the intercept module during the VOLSER locate request, is in process when interrupted by the job control module's exit. At that time, volume allocation for the data set recall is completed and the VOLSER request for the job control module can be satisfied. In the host processor, a job control module schedules all processes within the data processing environment. One of those processes involves the recall of data sets from various levels of a peripheral data storage hierarchy....