suggestions for SATA RAID cards

[Nikolas Britton]

On 8/23/06, Bob Willcox <bob at immure.com> wrote:
> On Wed, Aug 23, 2006 at 12:02:47PM +0200, Willem Jan Withagen wrote:
> > Steven Hartland wrote:
> > >The Areca cards I can recommend. Highpoint 1820a is surprisingly good
> > >for its price and the later cards have better performance still apparently.
> > >N.B. Use the min stripe size when creating the array for max performance
> > >with this card under FreeBSD.
> >
> > I was more thinking along the lines of a HighPoint 2720, but perhaps a 1820
> > would also do fine. What device driver would one use with that.
> >
> > [Ahhh, 'man -k highpoint' is your friend]
> > Now what I liked about the 3ware stuff was that there are tools to work the
> > raid from within FreeBSD. So that would require the newers ones...
> >
> > But the hardware list is only showing the 2320 and 2322 with a rr232x(4)
> > driver. Which sort of makes me wonder for all the other stuff and their
> > drivers.
> >
> > The motherboard has both PCI-X and PCI-E so that should not be a connector
> > problem. Now which bus is faster: 64Bit PCI-X at 133 Mhz, or a PCI-E 16x?
>
> The x16 PCI-E has considerably faster theoretical speed than 133 PCI-X
> (appx. 4GBs vs. 1GBs). However, the RAID controllers that I've seen are
> at most x8 so they are only capable of transfer rates half that fast
> (2GBs). Personally, I would go with PCI-E since in some performance
> tests I did with Areca cards last year (both PCI-E and PCI-X) there
> appeared to be a slight performance advantage to the PCI-E cards (sorry,
> I don't recall any of the specifics anymore, so please take that for
> what it's worth).
>

I agree. PCIe 8x is a faster bus and it's typically connected directly
to the MCH (north bridge) unlike PCI-X which is stuck on the ICH
(south bridge). Also the 2GB/s that was quoted for PCIe 8x is it's
one-way data rate "after" calculating in overhead. It's a dual simplex
interface meaning it has one path to send data and another path to
receive data. Imagine a simple two lane road.