Which question is easier to answer?
1: Select the storage platform which will serve all our needs for the next 3 years up to 10PB.
2: Select a standard disk drive to use in the next 5 servers we purchase.
Most people could answer #2 pretty easily with a little bit of information. It might take a day or two to figure this out. And if you get it wrong, what’s the worst thing that happens? You’re replacing 10 disks or so. #1 though, that’s harder – that requires knowing what you are going to be doing for the next 3 years, how much money you can spend, how much flexibility you are going to need, etc.
The cost of being wrong for question #1 could be millions of dollars.
The cost of being wrong for question #2 probably means a few thousand dollars.
You don’t always have the luxury of changing the question, but when faced with a decision that seems to be hard to make, look for ways to make it easier. One of the ways to make a question easier to answer is to lower the cost of being wrong. For question #1, how can you answer that question for the next year without excluding the possibility of expanding to 3 years? How can you get more data about your needs by starting small, gathering data, building understanding? How can you constrain the scope, not solve all your problems but solve the most pressing ones?
Try not to solve all your problems at once because there’s a good chance you aren’t going to succeed. Pick a problem, and do the simplest thing that works to fix that problem.