3. How much will it cost you to scale up?
The data explosion is all about dealing with continuous expansion. But with most storage vendors, the best deal you'll ever get from them is the first one. Down the road, when they know you are stuck with them, it can be a different story, so ask about add-on costs before you buy. Chances are you're probably buying at least one or two different kinds of disk for your storage solution, so have them give you quotes for various add-on options now. Nobody will really guarantee future pricing, but having the conversation up front will help keep them honest later -- and you'll find it easier to compare the costs of the solutions you're reviewing.
4. What is the TCO over the long term?
Very few organizations acquire a new primary storage solution and keep it in production for only three years. Even if it's rotated out of front-line production duty, chances are it's still active and doing relatively critical work through at least the fifth year. Be wary of vendors that hesitate to provide you with quotes for five years of support -- or at least solid estimates of what years four and five will cost. The ratio of support to hardware costs varies wildly between vendors, and when you reach the out years, the differences can be even more stark. Be sure to factor in those costs.
5. Is your prospective vendor a good partner?
Enterprise purchasing bears little or no resemblance to a trip to Best Buy. Switching costs are high, so like it or not, you're choosing a long-term partner. You're trusting this company to ensure that the most important part of your infrastructure will to function well and lend itself to being scaled, with as little disruption as possible, as your needs change. Are you confident -- both via references and your own intuition -- your relationship will stand the test of time? Like marriage, it's all about trust.
If any of this advice seems obvious, well, good. You're ahead of a lot of other buyers out there. I've seen some or all of these points overlooked in the past -- with serious consequences.
Or perhaps you have your own favorite litmus test that I haven't covered here. If so, leave a comment to this article and share them with the rest of us.