Shouldn't he wait until the cost comes down and settles a bit before he bothers writing a whole screed about the expense? It's like decrying the HDTV as not worth the money -- they're over $10,000 each! Or, they were, a few years ago.
Well, obviously the price of SSDs will change in the future, but the question is whether they are a good idea for server workloads now, not in 2 or 3 years.
The paper says "For each workload, we also calculated
the break-even capacity/dollar at which the best [SSD cache]
solution would equal the cost of a disk-based solution." Their results tell you exactly how cheap SSDs need to get before they're worth using. Given that SSDs have improved 5x-10x on several metrics since this paper, they are already suitable for some workloads.
Also, the paper finds that for many of their workloads performance effectively does not matter so SSDs will only be cheaper if they are cheaper per GB than disks, which will probably never happen. They're not saying that SSDs are too expensive; they're saying that SSDs will always be too expensive. It's not clear to me that this conclusion is correct, but it is interesting.
