No kidding, it's like a battery backed write cache doesn't even exist in the NoSQL world. I was able to easily drive 200MB/sec of random IO on 25 15K drives.
Btw, this was 200MB/sec of random writes. I didn't even bother with random writes. I could have gotten the writes to be basically sequential if I had bothered to write a COMB style UUID generator. I happen to be a fan of UUIDs for the surrogate keys as it makes database merging so much easier.
