On Tue, Jun 2, 2009 at 12:59 PM, Gordon Messmer <yinyang at eburg.com> wrote: > On 06/01/2009 07:52 PM, Michael A. Peters wrote: >> >> I've read a lot of different reports that suggest at this point in time, >> kernel software raid is in most cases better than controller raid. > > There are certainly a lot of people who feel that way. It depends on > what your priorities are. Hardware RAID has the advantage of offloading > some calculations from the CPU, and has a write cache which can decrease > memory use. However, both of those are relatively expensive, and > there's no clear evidence that your money is better put into the RAID > card than into faster CPU and more memory. Another important > consideration is that hardware RAID will (must!) have a battery backup > so that any scheduled writes can be completed later in the case of power > loss. If you decide to use software RAID, I would strongly advise you > to use a UPS, and to make sure your system monitors it and shuts down in > the event of power loss. I'd advise anybody who manages server equipment always UPS it. It's not just power losses that can ruin your day, a power spike can take out a power supply just as easily and a UPS conditions the power so the output level is constant. -Ross