Sérgio Lima Costa wrote: >The people here, want split the cost of Mainframe to users that use it. >For example, the user consumed 10% of CPU, then the cost of CPU is $40.000,00. >So for this user, the price was $4.000,00. >This is only a example.
But your mainframe's economics doesn't work that way.(*) Moreover, if those people set up a chargeback system with that sort of formula, they're likely to cause serious IT (and financial) problems for your employer. Here's a simple counter-example. Let's suppose you have 10 users each consuming 10% of CPU, and you charge each user $4,000. Now one of those users decides to stop using the mainframe. Your formula then collects $36,000. Is the total cost still $36,000? No. It's much closer (or even equal to) $40,000. (Did you fire 10% of your IT staff?) So would you then charge the 9 remaining users ~$4440 each? Why? They didn't do anything, and nothing changed in the costs. See the problem? That average cost formula, among other things, fails to take into account the difference between marginal costs and fixed costs. And what happens is that cost-driven users (most/all are) then have perverse incentives to do all sorts of crazy things. [Sound familiar? :-)] That's why you're getting lots of questions about "why?" There are tools, lots of tools, highly developed and refined. They're useful, but you can also do really dumb things with those tools, like charge users average costs. Please don't. Bad chargeback systems are much, much worse than no chargeback systems. What problem(s) are they trying to solve? (*) *Any* highly virtualized infrastructure has this core financial characteristic. The whole IT world is preaching the virtues of highly virtualized infrastructure, including cost savings. Effective sharing of any resources, including computing resources, is highly cost-efficient. But if you institute a chargeback system which actively discourages users from sharing HVI, what do you think is going to happen? What has happened, with terrible business consequences, in too many cases? What is the IT world now spending considerable effort trying to un-do? -------------------------------------------------------------------------------------------------------- Timothy Sipples Resident Enterprise Architect (Based in Singapore) E-Mail: timothy.sipp...@us.ibm.com ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN
