[leokennis]

Well...you sort of “pay for what you use”. I believe the extremely simplified version is you pay for the peak CPU usage (excluding specialty processors like ZIIP) in a moving 4 hour average window.

Context: I work for a large organization that used to run several physical Z13 mainframes, all of them containing several sysplexes. If we had issues, an IBM consultant would fly in within the day. We were definitely not IBM’s biggest customer but we were not insignificant for them either.

We had a lot of mainframe support staff (so not people programming for mainframe but people maintaining storage, DB2, z/OS upgrades etc.) and I think even for them, the IBM bill was more or less: we see a large number, no idea why it’s this amount, but we cannot prove it is not right, so I guess we’ll just pay it.

Mainframe billing is really complicated.