Thanks Tim and Kees for your clarifications. The 'hour' doesn't mean anything then.. ? from the MSU definition (MSUs is an hourly measure (A million service units (MSU) is a measurement of the amount of processing work a computer can perform in one hour)
For the vendor bit... Assuming my machine's capacity is x MSUs and a vendor's contract specifies a usage limit of y MSUs (where y is slightly less than x), One of these 2 things must be true - a) the vendor is probably rounding down a bit, from the machine's capacity b) vendor has some mechanism to check and arrest usage real-time. - Vignesh Mainframe Infrastructure -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Timothy Sipples Sent: 17 October 2017 08:11 To: [email protected] Subject: Re: Potential stupid question - MSUs Vignesh Sankaranarayanan wrote: >1. If a machine is rated at, for example, 655 MSUs, does this mean >that it can go on up to 655 total MSUs in an hour or 655 at any instant It can run at 655 MSUs for any length of time the machine is running. As an analogy, imagine that you have an engine that is capable of running at up to 2700 revolutions per minute (RPMs) continuously. (Some aircraft engines are exactly like this.) That means you can run the engine for 5 seconds at that rated speed, 5 minutes, or 5 hours. As long as you have enough fuel, I suppose. But it's all still at the same maximum output over that period of time: 2700 RPMs. Now, just because the propeller is spinning at 2700 RPMs doesn't necessarily mean it's doing *useful* work or generating any particular amount of real-world output (thrust). That's a separate concept. If the airplane engine is bolted to a stationary test stand, for example, there's no flight happening. That's also true of mainframes and MSUs. Those MSUs can be spent running a mission critical sort job, or processing credit card transactions, or Tweeting lines from Shakespeare's plays, or all of the above concurrently. Whether those particular workloads are "useful" is a separate question. Extending the analogy, some engines have a rated time limit at certain output levels, so they might allow 2800 RPMs for up to 5 minutes, up to 2600 RPMs otherwise. In aircraft engines that's fairly common, and it's usually called "maximum takeoff power" or something like that. In z/OS a broadly similar concept is possible, colloquially called a "softcap." Water, oil, and gas pipelines are conceptually similar. They allow a maximum flow rate, in liters per minute for example, and you can send up to that flow rate through the pipeline for any length of time -- for 5 seconds, for 5 hours, for 5 years, assuming the pipeline is in good operating condition. It's all the same basic idea. >2. If a vendor's license says, "you can run it on cpu xyz", and the >contract says 500 MSUs, does this again mean an hourly 500 total MSUs >or 500 at any given instant. Unless the contract is quite unusual, it *probably* means the same thing as above, but that's perhaps for courts and lawyers to decide if there's a dispute. And it's possible that the vendor has their own, separate definition for "MSUs." You could always ask the vendor, of course. -------------------------------------------------------------------------------------------------------- Timothy Sipples IT Architect Executive, Industry Solutions, IBM z Systems, AP/GCG/MEA E-Mail: [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN MARKSANDSPENCER.COM ________________________________ Unless otherwise stated above: Marks and Spencer plc Registered Office: Waterside House 35 North Wharf Road London W2 1NW Registered No. 214436 in England and Wales. Telephone (020) 7935 4422 Facsimile (020) 7487 2670 www.marksandspencer.com Please note that electronic mail may be monitored. This e-mail is confidential. If you received it by mistake, please let us know and then delete it from your system; you should not copy, disclose, or distribute its contents to anyone nor act in reliance on this e-mail, as this is prohibited and may be unlawful. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
