(1) The definition of "bunch" depends primarily on the size and number of VM's you need to auto-restore, and can be as few as 2!! This is at 50% utilization......maybe not "practical" at this number, but still only at (n-1)/n utilization for all other cases!!......which doesn't sound nearly as bad as simply saying "a bunch", imo!! (i.e. with only 4 ESX servers running at 75% utilitzation, I may be able to support a complete failure of one of those physical servers! considering that I may not have to worry about having any "test" and "dev" environments auto-restore, and I can probably even do better!!)
(2) I find that the flexibility I gain with virtualization and the increased recovery time of my environment often offset the costs of any infrastructure improvements that I may need to perform in order to support it!!
(3) Having seen virtual environments "certified" in regards to the segregation of data (even for evidentiary purposes!!), I don't find myself in the camp that says you have to buy separate physical equipment in order to effectively segregate data. You just need to know how to set up your environment!!
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