suggestions for SATA RAID cards

[Nikolas Britton]

On 8/23/06, Nikolas Britton <nikolas.britton at gmail.com> wrote:
> 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.
>

I take that back. For PCIe 8x imagine a divided highway with 8 lanes
in each direction. The speed limit for each lane of traffic is
250MegaBytes/sec. So if you can move 8 semi-trucks filled with data in
parallel your effective data rate is 2GigaBytes/sec. simple eh? :-)


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