Re: performance on new linux box

On Jul 14, 2010, at 6:57 PM, Scott Carey wrote:

> But none of this explains why a 4-disk raid 10 is slower than a 1 disk system.  If there is no write-back caching on
theRAID, it should still be similar to the one disk setup. 

Many raid controllers are smart enough to always turn off write caching on the drives, and also disable the feature on
theirown buffer without a BBU. Add a BBU, and the cache on the controller starts getting used, but *not* the cache on
thedrives. 

Take away the controller, and most OS's by default enable the write cache on the drive. You can turn it off if you
want,but if you know how to do that, then you're probably also the same kind of person that would have purchased a raid
cardwith a BBU.