> But - he's comparing one mid-range sun to one z/900. Seems like > the 37% people and remainder facilities would be the same in both > of those. One sun should be just about as much work/power as one > z/900.. in fact, I'd expect one mid-range sun to be a little lower > on the power/HVAC requirements.
This is probably more garbled than I want it to be, but I'm short of time, and running out of battery in the laptop. For *one* application, one box, he's probably ok. It's taking the larger view of the fact that most organizations don't have only one application, nor do they have one box per application. Let's think about box count first for a moment. Consider that for most organizations, when you deploy Application X's server in production you need some extra hardware to make the solution supportable. You need: 1) the production box itself 2) a backup server or hot spare in clustering environment (we are talking mission crit apps) 3) a development box 4) a test/QA box 5) possibly a regression box in case more than one version is in production at any given time. So, the comparison of one z900/z800 is actually against 4, possibly 5 Sun boxes per application deployed. You can't double up on the test systems because you need them to mirror production to be a valid test; and you sure don't want developers testing on the same box. So, assuming worst case of 5 boxes per application, we've erased most of that 18% number down to about 2-3% overall. What happens when the next application comes along, call it Application Y? You now need new boxes for that application. Can't use the others because they're dedicated to application X. So, for Application Y, you now need 1+4 *more* servers. We're now up to 8 servers for two applications. The trend is clear. Note that we have not addressed the floor space or power costs yet -- which increase each time we add a server. We also can assume no sharing of resources; they're separate boxes, and you can't move MIPS or I/O w/o disrupting service. We also are not computing additional overhead for maintenance (you get a lot of that for free with VM; the Linux stuff takes some thought to do, but is also doable with a much higher level of automation). The real kick for most people is while the initial cost of the zSeries is high; it amortizes quickly across multiple applications -- if you take the model above where you need 4-5 servers to deploy an application, a solution where the same physical server handles that load and gets partitioned to supply the same configuration logically, your cost per application decreases substantially -- 1/n instead of n*4 or more. The part he's missing in the article is that in the case of applications n+1 and n+2, there is not necessarily a hardware acquisition component, or an additional facilities costs, which are substantial, but fixed for the duration of the capacity available in the z800/z900, which can be overlapped for normal applications (the case of applications using 100% of the box is vanishingly rare). The steps for environmentals and staff are larger, but much less frequent. > So - then the argument would be that for 16.4% more, you can get > all of the RAS of z/900 hardware, vs. the mainframe box. Is that > a fair statement? Not really. The major argument is that you control the cost of deployment and operations rather than focus on cost of hardware for a *number* of applications, not just one, and that the investment you make in support infrastructure and staffing is overall smaller for the same number of logical images. That cost is coming out of the 70+% of the TCO, and is much more likely to be recurring cost, which is what makes any solution expensive.
