On Thu, Jul 8, 2010 at 12:46 PM, Kevin Grittner <kevin.gritt...@wicourts.gov > wrote:
> Ryan Wexler <r...@iridiumsuite.com> wrote: > > > One thing I don't understand is why BBU will result in a huge > > performance gain. I thought BBU was all about power failures? > > Well, it makes it safe for the controller to consider the write > complete as soon as it hits the RAM cache, rather than waiting for > persistence to the disk itself. It can then schedule the writes in > a manner which is efficient based on the physical medium. > > Something like this was probably happening on your non-server > machines, but without BBU it was not actually safe. Server class > machines tend to be more conservative about not losing your data, > but without a RAID controller with BBU cache, that slows writes down > to the speed of the rotating disks. > > -Kevin > Thanks for the explanations that makes things clearer. It still amazes me that it would account for a 5x change in IO.
