Thanks again for taking the time Tim. It does make sense, of course.. the concept of a max. available flow rate.
You guys have already clarified in your previous replies but for some reason, I just can't fathom a vendor leaving the enforcement of a rule up to a customer, and letting the contract (something completely detached from the machine) be the only binding factor. Of course there may be audits on the CPU usage but it seems strange to let someone cross a threshold and then charge them for it rather than warn/limit them (their usage) real-time. - Vignesh Mainframe Infrastructure -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Timothy Sipples Sent: 18 October 2017 06:23 To: [email protected] Subject: Re: Potential stupid question - MSUs Vignesh Sankaranarayanan wrote: >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) Yes, it means something. I'll try again: think of MSUs as a flow *rate*, "X tasks per hour." I'll try another analogy. Let's suppose you own a factory, right now it has 6 employees, and each employee can make 3 shirts per hour. That's a total of 18 shirts per hour -- "18 Made Shirt Units (MSUs) per hour." Make sense so far? Let's further suppose that you can add employees and increase output linearly. So if you double the number of employees to 12, then your factory can output 36 MSUs per hour. Or cut the number of employees to 3, and you now have a 9 MSU factory. OK, now the government steps in and imposes a tax based on your MSUs. The tax is 200 rupees per MSU per month, minimum 600 (the tax on 3 MSUs). The tax is based on the maximum number of employees in your factory during the last month. So, for example, to calculate the tax bill for last month (September), the government sees that you had 8 employees working on September 2 between the hours of 10:00 a.m. and 2:00 p.m., and that was your maximum for the month. So your factory had a peak of 24 MSUs (8 employees times 3 shirts per hour), thus they send you a bill for 4,800 rupees (24 times 200 rupees per MSU). MSUs is a flow rate measure, that's all. That doesn't mean your factory (mainframe) *must* run at its maximum flow rate for any length of time, or for any time at all. But the factory (mainframe) is *capable* of running at that maximum flow rate, given a particular number of employees ("MIPS"). Yes, you can tell your factory employees to come to work (to the factory) and stay on duty, but not to sew any shirts. If the total staffing on shift is 10 employees, for example, then you have a 30 MSU factory in this example. But whether those 30 MSUs of factory *capacity* are producing useful output or not is a separate question. Or you could tell those 10 employees to sew 1 shirt per hour, even though they are capable of 3 shirts per hour -- you can make the 30 MSU factory run at 10 MSUs. Or you can tell the employees to sew 1 shirt during the first 20 minutes of each/every hour and then to take a 40 minute coffee break for the remainder of each/every hour. So for the first 20 minutes of each/every hour the factory runs at 30 MSUs, and then for the last 40 minutes of each/every hour the factory runs at 0 MSUs (but is capable of running at 30 MSUs). That's possible, too. Or you can tell those 10 employees to trade turns at one sewing machine in the factory, in 6 minute shifts. If you do that, then that's just like having 1 full-time employee (assuming no switching overhead), and so you get 3 MSUs of output (3 Made Shirt Units per hour). Does all this make sense yet? The concept of a maximum flow rate (whether utilized or not, at any particular moment in time) seems pretty simple to me, but maybe I'm not explaining it well if it's still confusing. -------------------------------------------------------------------------------------------------------- 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. 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