What Goes Up Must Come Down
No, scalability may not be rocket science but it is computer science and not nearly as easy as it might appear
In what might be considered an ironic statement, scalability in cloud computing environments is as much about decreasing capacity as it is increasing capacity.
I know, puts my knickers in a twist, too.
The description of “scalability” associated with cloud computing in almost every definition that’s put forth1, however, clearly indicates the need for elastic scalability and it is that modifier that makes all the difference in the world.
See, in the past we’ve just been concerned with managing growth, with addressing the need to increase capacity to match an increase in usage. It may have been slow and steady or explosive and instantaneous, but it was always about an increase in usage. We never really considered how to deal with a decrease and we certainly didn’t take away capacity once we’d allocated it.
Cloud computing, however, does assume that the latter is something we will – and should – do.
Cloud isn’t just about “pay for what you use” it’s also about “use only what you need” and thus transitive logic tells us2 it should be “pay for what you need”. It’s about efficiency of utilization as much as it is costs. And efficiency means use what you need, when you need it, but no more. Do not tie up resources when they aren’t needed, let someone else use them. It’s about the allocation of capacity in a way that makes sense, without waste.