4-hour MSU rolling average.

[alpna]

Hi,

What is the meaning of "4-hour MSU rolling average"? How and where we use it? How it relates to mainframes?

[Robert Sample]

MSU is millions of service units, a measure of CPU usage. IBM supports use of sub-capacity licensing, which reduces the charge for a mainframe where the company is not using the full capacity of it. Sub-capacity licensing can substantially reduce the cost of a mainframe to a company. The metric for sub-capacity licensing is a 4-hour MSU rolling average (that is, the average MSU used during each 4-hour period of a month) and the license charge is based upon how much capacity is used.

The term is used specifically for IBM license charges on a z/OS machine where the company cannot afford (or cannot use) the full capacity of the machine.

[alpna]

Thanks. So is there something more like 1 hour-, 2 hour-rolling average too? Are there some specific set of rules which IBM publish for this?

If I need to a assessment exercise for a client who is using 4-hour MSU rolling average what are the thing I should consider? Please hep with your guidance.

[Robert Sample]

As far as I know, IBM uses ONLY the 4-hour average for license charges. You can, of course, compute 1-hour or 2-hour (or 17-hour) rolling averages but they are of no interest to IBM as far as license charges go.

With sub-capacity pricing, you need to consider the impact of changes. Shifting part of the batch workload a few hours may reduce batch costs -- but if the shift moves part of batch into the time the online systems are up, the 4-hour average may well go up and thus impact costs. What are you supposed to be assessing?