Chris,
> I don't know so much about FreeBSD's handling of this, but on Linux,
> there's pretty strong indication that _SOFTWARE_ RAID is faster than
> hardware RAID.
Certainly better than an Adaptec. But not necessarily better than a
medium-end RAID card, like an LSI. It really depends on the quality of the
controller.
Also, expected concurrent activity should influence you. On a dedicated
database server, you'll seldom max out the CPU but will often max of the
disk, so the CPU required by software RAID is "free". However, if you have
a Web/PG/E-mail box which frequently hits 100% CPU, then even a lower-end
RAID card can be beneficial simply by taking load off the CPU.
--
Josh Berkus
Aglio Database Solutions
San Francisco