Last week Jason Bloomberg of ZapThink wrote a funny, cutting piece that was meant to rip the notion of the private cloud to shreds.
I actually found myself agreeing with some of it -- but not with the blanket conclusion that "private clouds suck."
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Let's take Bloomberg's points one at a time. His first is that people associate "the cloud" with public cloud services, where customers pay as they go for the resources they use rather than investing in infrastructure. With a private cloud, the customer necessarily owns the infrastructure, plus private cloud management software on top of that, so it's a capital expense like anything else you own rather than rent.
OK -- but isn't that why it's called "private"? If you don't get that distinction in a minute or two, maybe IT isn't the career for you.
A better argument can be found in Bloomberg's main point: In a private cloud, you'll never have anywhere near the ability to accommodate spikes in demand as with a public cloud, because public cloud facilities are massive pooled resources and private clouds are only as elastic as you're willing to invest in capacity to begin with.
True enough. Although I often hear about repurposing dev and test capacity to meet spikes in demand for production Web applications, Bloomberg is right. There's always a hard limit to scaling the private cloud.
His related point on this score is also correct: Because of that limit and the fact that the owner of the private cloud is typically the only tenant, the economies of scale running a private cloud can never match those of a public cloud.
Finally, Bloomberg makes a subtler point: Clouds of any stripe tend to require homogenous infrastructure. Can you say "rip and replace"?