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List:       gentoo-sparc
Subject:    Re: [gentoo-sparc] SCSI controller?
From:       Keith M Wesolowski <wesolows () foobazco ! org>
Date:       2005-01-09 17:50:33
Message-ID: 20050109175033.GA27710 () foobazco ! org
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On Sun, Jan 09, 2005 at 10:21:04PM +1300, Chris Russell wrote:

> not sure what the Qlogic/PTI controllers are available as but since you
> are plugging it into a 25MHz SBUS beware of the bus's throughput
> limitations.

The fastest qlogic controller made for sbus was an ultra/wide version.
So it can do 40 MB/s.  However, that controller has been flakey for
some people, including me, using the driver that's in Linux.  I know
of no workaround nor do I know the cause.

That this is a bus limitation is a common misconception.  In fact sbus
is faster than standard pci (theoretical maximum: 64 bit x 25 MHz > 32
bit x 33 MHz) and could support a 160 MB/s controller if any had been
made.  It's moot, though, since they weren't.

> > > And sometimes harddisk stop responding upon large write operation, 
> > > people on the list suggest this could be because of broken SCSI 
> > > controller. So I think, if QLogic PTI controller is faster, perhaps I 
> > > could just buy one and stop using on-board controller.
> 
> I don't think this is likely, normally they would work completely or not
> at all, there is only a small chance of a 'broken' controller failing
> intermittently.  If anything, I'd be checking cable termination etc..
> (from memory the cable loops off the board to the CD-ROM and back again
> so perhaps check the termination jumper of the CD-ROM drive is not set)
> refer to the manual for jumpers etc...

Well, I've seen behaviour similar to this using the aforementioned
qlogic controller, but never with esp unless there's some other
problem.  The esp driver ought to be very reliable.  You probably do
have hardware problems, but I agree with cjr that it's probably not
the controller.

-- 
Keith M Wesolowski
"Site launched. Many things not yet working." --Hector Urtubia

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