Re: [Bug 12309] Large I/O operations result in slow performanceand high iowait times

From: Henrique de Moraes Holschuh
Date: Sat Apr 03 2010 - 22:08:35 EST

On Sat, 03 Apr 2010, Thomas Pilarski wrote:
> > > This problem is enormous increased, while the ultra bay disc is acceded
> > > with udma2 instead of udma6 (caused by another bug),
> >
> > There is a thinkpad BIOS bug that could cause that: it will not signal a
> > 80-wire cable when you hot-add an HD on a PATA ultrabay. Exists at least on
> > all T4x, including the T43.
> It's a SATA untrabay disk. There is a 40-wire message, but sometimes it
> works and sometimes not. I could not figure out, when it does and when
> not.

Which ThinkPad model? And yes, if it is the BIOS 40-wire problem, it
doesn't show up always. I keep forgetting exactly how to trigger it (I
think it is hotplug device when you boot with the bay empty), but it is
100% reproducible.

> > The fix is to whitelist these thinkpads for high-speed UDMA even on 40-wire
> > cables. The workaround is to add a kernel command line parameter (I forget
> > which).
> >
> > Does that match your udma2 instead of udma6 problem?
> Thanks. I will try it. But have to finish another project first.

Just make sure to tell me if the ata 40-wire short cable override fixes
your problem when you get around to trying it.

"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
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