Because EBS has astonishing variance in its response times that cause the entire raidset to have very inconsistent performance. Numbers here: http://www.mysql

Because EBS has astonishing variance in its response times that cause the entire raidset to have very inconsistent performance. Numbers here: http://www.mysqlperformanceblog.com/2011/02/21/death-match-ebs-versus-ssd-price-performance-and-qos/ http://www.mysqlperformanceblog.com/2011/02/21/death-match-e... In order for raid-on-ebs to truly perform well you have to setup per-volume monitoring that ejects volumes from the raidset (and runs in degraded mode) when they start performing 10x worse, and then rebuilds the back on to it (or a new one) later. It becomes a rather arcane wizard work contraption of on-the-fly raid config changes, which IMHO qualifies as "insane".