Re: aic7xxx bus speed

Justin T. Gibbs (gibbs@scsiguy.com)
Tue, 15 Jan 2002 08:50:04 -0700

>Hi
>I've an aic7899: Ultra160 Wide scsi controller with a few disks
>under an alpha ds20 running.
>Now I'm having troubles getting 160MB/s bus speed on the
>actual kernels (2.4.18pre2/2.5.2pre9). On the kernel 2.2.18 and
>the redhat kernels 2.4.3-12, 2.4.9-13 I get full speed of 160MB/s.
>But on the new kernel I get just 80MB/s per bus.

You probably have IBM drives that say they are SCSI-2 yet can do
160 speeds. There is a check in the driver that prevents it from
negotiating from SCSI-2 drives so as to not blow up on SCSI-2 devices
that don't support the new negotiation message type. I have a fix
to work around IBM's mistake in the next driver release.

--
Justin
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