Who are your friends? Anyone can tell you what you want to hear, but your friends will also tell you what you don’t want to hear.
Today, I am going to be your friend. I happen to know that there are still a large number of you still running systems with 18GB and 36GB drives. Most know that NetApp doesn’t make those anymore. A smart person may think that there won’t be a big demand for older smaller drives, so there will be plenty available for a long time. So they will hold on to those systems and be able to replace those drives, cheap, for a long time. An even smarter person will realize there are a lot of smart people out there holding on to those systems and the demand for a finite quantity of drives may drive the price up or even deplete the supply.
What am I trying to say? If you have one of these systems, and you don’t have the need to upgrade, you might want to start picking up some spare drives. Zerowait has them, but even Zerowait is beginning to have a hard time finding more out there. You may even want to pick up ZPA hardware support from Zerowait. Then you wont have to find the drives, Zerowait would find them for you!