Ultra160 controller on 32bit pci

Ultra160 controller on 32bit pci

[Mogens Valentin]

Currently using Adaptec 29160, works fine, but it's only 160/2, after
all.
I'm curious if other controllers can provide better performance when
used on a 32bit pci bus?

In a few month I might switch to a pci-express/opteron setup, so I'd
like some indication about controllers for that bus.

I'm using two u320 10K disks + one fast10 device on a development
server/workstation, so I don't need an interprise-level ctrl.; but both
the pci32 and pci-express thingy should preferebly provide a narrow
connector as well.


I'm not currently on the scsi list, so if anyone would care to shed some
lights, please address me directly.
Thanks.

-- 
Kind regards,
Mogens Valentin
Networking, Security
www.danbbs.dk/~monz
Phone +45 32 525 878

Re: Ultra160 controller on 32bit pci

[Matthew Wilcox]

On Thu, May 06, 2004 at 10:15:04AM +0200, Mogens Valentin wrote:
> Currently using Adaptec 29160, works fine, but it's only 160/2, after
> all.
> I'm curious if other controllers can provide better performance when
> used on a 32bit pci bus?

Theoretical bandwidth on a 33MHz 32-bit PCI bus is around 132MB/s.
In practice you never attain that because of overhead in turning the bus
around and typical figures quoted in the PCI spec are between 60-107MB/s.
So you already saturated the PCI bus (never mind what else you have on that
bus).

> In a few month I might switch to a pci-express/opteron setup, so I'd
> like some indication about controllers for that bus.

Depends what people are going to ship.  I've heard rumours the initial
chipsets will have an x16 link for graphics and an x4 link for other I/O.
Express gives you 256MB/s in each direction for an x1 link, so expect
to get 1GB/s *in each direction* from an Express SCSI card.  Will there
be parallel SCSI Express cards?  Not sure, everything seems to indicate
SAS instead.

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain

Re: Ultra160 controller on 32bit pci

[Mogens Valentin]

Matthew Wilcox wrote:
> 
> On Thu, May 06, 2004 at 10:15:04AM +0200, Mogens Valentin wrote:
> > Currently using Adaptec 29160, works fine, but it's only 160/2, after
> > all.
> > I'm curious if other controllers can provide better performance when
> > used on a 32bit pci bus?
> 
> Theoretical bandwidth on a 33MHz 32-bit PCI bus is around 132MB/s.
> In practice you never attain that because of overhead in turning the bus
> around and typical figures quoted in the PCI spec are between 60-107MB/s.
> So you already saturated the PCI bus (never mind what else you have on
> that bus).

I'm aware of that. I have a 40MHz pci bus, no problems with any devices
(most modern cards are build for 66MHz anyway), so I'm interested in
scsi controllers possible utilising a 32bit interface better (than the
29160).
Haven't seen any though, thus the question.

> > In a few month I might switch to a pci-express/opteron setup, so I'd
> > like some indication about controllers for that bus.
> 
> Depends what people are going to ship.  I've heard rumours the initial
> chipsets will have an x16 link for graphics and an x4 link for other I/O.

Yes, a few such boards already exist. No matter which combinations will
be on boards, I'll be happy with on x16 slot for video and one
x-whatever for a scsi controller.

Thanks for replying..

-- 
Kind regards,
Mogens Valentin
Networking, Security
www.danbbs.dk/~monz
Phone +45 32 525 878