SSDs are still grossly slower than RAM. The fastest SSD I know of is the Intel 750, which is like ~2.0 GigaBYTES&#x2F;second (or for what is more typical for storage benchmarks: about 16Gbps or so over PCIe x4).<p>Main DDR3 RAM is something like 32GigaBYTES per second, and L1 cache is even further.<p>What I think the poster was talking about, is moving from disk-based databases to SSD-based databases. SSDs are much faster than hard drives.<p>L1 Cache, L2 Cache, L3 Cache, and main memory are all orders of magnitude faster than even the fastest SSDs today. Thinking about the &quot;CPU prefetcher&quot; when we&#x27;re talking about SSDs or Hard Drives is almost irrelevant due to the magnitudes of speed difference.