It's important to figure out where the line is between planning for a little growth and flat out over provisioning.
It's a combination of the cone of uncertainty combined with early investment. Even if you knew 100% that you'd need twice as much capacity in five years, still wouldn't make sense to buy it today.
Right. But if I'm already using 1.9 of 2TB of storage, it would make more sense to upgrade to 3TB or 4TB rather than make a huge jump to 9TB or 12 TB just because we predict that kind of growth even 3 years out.
Can't answer that without looking at cost differences, projected growth, etc.