So which do you think is cheaper?
> Unification, consolidation, simplification – it sounds attractive. But not when you take the real world into account
On the one hand, we have buying in bulk from a couple of preferred vendors (obviously, not going with a single supplier - that would be utterly insane, for so many well-known reasons) where you can play one off against the other. With the discounts that come from buying significant amounts of "stuff" and with the leverage to extract cheap or free support with the tacit threat that you'll drop them instantly if they fail to deliver.
On the other we have every designer or project choosing their own hardware, O/S and applications based on what glossy they got through the post that morning, or which vendor's sales lady (or gent) is prettiest, or even what course they did at secondary school. Ending up with a mix of Dell, HP, Sun (ok, that was a joke), various flavours of Linux, W/Server 200x, Unix, Oracle, SAP, and a dozen others. All needing specialised support staff on site, all needing their own upgrade schedules, test environments (ok, that was the other joke), backups, DR, patches, bug-fixes and support contracts. None of which amount to a sizable enough stake for any particular vendor to hand out special terms and with third party support which, likewise, involves hanging on the phone for a slow-reading voice to ask if you've tried rebooting.
While this first option may well tie you in to a particular regime, the costs involved in being able to deploy cheap, generic hardware - that can be swapped around, reallocated and load-balanced in next to no time, and cheap generic support staff who will line up outside your head office at the merest hint of a vacancy,, is hugely attractive. Especially when you consider that the average engagement time of an IT director is measured in a few years, so they'll reap the rewards of the cost savings without making the mistake of sticking around to clean the **it off the fan - and you can see why data centres look more like a stockroom for blade servers, than the diverse environment of a computer fairground.