I can't imagine that SSDs would make any difference for web app servers. I am not familiar with app servers workload that uses a material amount of disk I/O.

I can't imagine that SSDs would make any difference for web app servers. I am not familiar with app servers workload that uses a material amount of disk I/O. That being said, if I built custom app servers, I'd use SSDs because the cost is small for a system that doesn't need much storage.