Thomas Kern writes:
>I would use CPU seconds rather than Service Units. Managers can understand
>that there are only 86400 CPU seconds per engine per day. If you can get
the
>price paid for your z9, take 1/4 of that and divide by 365*86400 to get a
>price per CPU second. This would recover the cost of the z9 in 4 years.
I've said this before, but just be very, very careful. What you're
describing is a measure of the (medium-term) *average* (hardware?) cost per
CPU-second. The average cost is very substantially different from the
marginal cost of processing an additional CPU-second, which is much more
nearly zero. Said another way, in capital investment economics marginal
costs are almost always lower than average costs -- in mainframe economics
much lower -- except perhaps at specific, individual price discontinuities
("stair steps"). For a price discontinuity example, if you're running a
System z9 BC Model Z04, i.e. a machine with all CP capacity enabled, then
the marginal cost of the next MIPS requires moving to an EC model and the
associated upgrade expense. Nowadays mainframe computing arguably has fewer
price discontinuities than distributed computing.
Folks, it's super-critical managers understand this phenomenon. Otherwise
you get all sorts of really weird and perverse behaviors.?)
Honestly I don't think the average cost is particularly meaningful.
Marginal costs are much more interesting and valuable.
As a general rule, mainframe economics are characterized by decent (but
steadily declining each year) initial fixed costs, low (and steadily
declining each year) marginal costs, and progressively lower marginal costs
as workload grows ("the curve"). There are some nuances for each major
component of those costs (staff/services, hardware, software, and
facilities/network), but that's the general rule by the time you add it all
up. Your mileage may vary, but if that's not what you're experiencing it's
worth investigating.
- - - - -
Timothy Sipples
IBM Consulting Enterprise Software Architect
Specializing in Software Architectures Related to System z
Based in Tokyo, Serving IBM Japan and IBM Asia-Pacific
E-Mail: [EMAIL PROTECTED]
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