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HP OpenVMS Systemsask the wizard |
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The Question is: Is the scheduler, e.g. the usage of quantum/iota significantly changed in AXP/VMS V7.2 compared to VAX/VMS 6.2....? It can be demonstrated, that the dynamics of OpenVMS are completely different from the "old times". If there is only ONE compute bound job (prio=4) without any i/o or paging on the system (DS10), then the behavior of the system is extreme sluggish, e.g. mc sysgen show quantum does take 40 seconds in a second decterm? (quantum is 10, iota=1). I did encounter the same kind of problems on axp 4100 multiple cpu mashines, but never had a chance, to track the user (stock traders) complaints in any way, so we had been having this kind of non-traceble problem for more than 2 years, most of the time, the extra cpu's on the 4100's did circumvent the problem. The Answer is : It can be demonstrated that OpenVMS has changed significantly from "old times" in a variety of ways. Old rules-of-thumb and older tuning techniques may or may not be applicable to newer OpenVMS releases and/or to particular OpenVMS VAX or OpenVMS Alpha systems. As for one discussion of a change related to the processing around QUANTUM, please see topic 4341 here in Ask The Wizard. The value of IOTA defaults to 2, and changes to it generally also involve a (recommended) discussion with Compaq Customer Services. Without significantly more information on the system configuration (hardware, software, settings, etc), the OpenVMS Wizard is not in a position to assist with tuning and site- and configuration-specific issues. Please contact the Compaq Customer Support Center directly for assistance in tuning the system, and for assistance meeting the particular system responsiveness requirements.
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