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Input/Output Load Balancing Method

IP.com Disclosure Number: IPCOM000079970D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Page, JB: AUTHOR [+2]

Abstract

The VS2/R2 (Virtual System 2/Release 2) I/O Load Balancing method employs address space swapping as its control mechanism. When such a correcting swap takes place, all of a job's (or TSO command's) I/O load either disappears (in the case of a swap-out) or reappears (in the case of a swapin). When it is the case that a job's data sets are widely distributed across many logical channels, the swapping of that job will effect the load on all of these channels and will probably not have an entirely satisfactory correcting effect on a known set of I/O load imbalances. The reason for this is, that there is a very low probability that the set of currently over or underloaded channels will coincide precisely with the channel dependencies of a job with widely distributed data sets.

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Input/Output Load Balancing Method

The VS2/R2 (Virtual System 2/Release 2) I/O Load Balancing method employs address space swapping as its control mechanism. When such a correcting swap takes place, all of a job's (or TSO command's) I/O load either disappears (in the case of a swap-out) or reappears (in the case of a swapin). When it is the case that a job's data sets are widely distributed across many logical channels, the swapping of that job will effect the load on all of these channels and will probably not have an entirely satisfactory correcting effect on a known set of I/O load imbalances. The reason for this is, that there is a very low probability that the set of currently over or underloaded channels will coincide precisely with the channel dependencies of a job with widely distributed data sets. Accordingly, the swapping of such a job may remedy some imbalances but it will also probably aggravate others. If, however, a job's I/O dependencies were localized to a single logical channel, there would be a high degree of certainty that swapping the job in order to correct an imbalance known to coincide with the job's channel dependency will have the intended correcting effect.

In practice, it is not always possible to restrict a job's I/O dependencies to a single channel, but any success in reducing a job's I/O dependencies will improve the value of the job as a candidate for correcting I/O load imbalances. Accordingly, the SRM (System Resource Manager) device allocation method uses as its...