Promise Ultra ATA 66 controller vs. FC1

[Alexander Dalloz]

Am Fr, den 23.01.2004 schrieb Alexander Dalloz um 20:27:
> Am Fr, den 23.01.2004 schrieb Robert D. Arendt um 19:18:
> > Steve Saady wrote:
> > > I have a Promise Ultra 66 eide controller, but think it is only being 
> > > acessed at 33 Mhz.  I have looked around, but have not found how to 
> > > ascertain what rate Fedora is using it at.
> > > Is there a way to configure FC1 to use it at 66MHz?
> > > 
> > <snip>
> > > 
> > > dmesg|more :
> > > ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
> > > 
> > I added idebus=66 to /etc/grub.conf, so my boot line now looks like:
> >    kernel /vmlinuz-2.6.1-1.53smp ro root=LABEL=/ apm=off idebus=66
> > should work with the nominal FC1 kernel as well.  Really boosted my
> > disk I/O speed.
> > 
> > Hope this helps,
> > -Bob Arendt
> 
> What kind of hardware are you running - no PC ware or even very old EISA
> bus hardware?
> 
> idebus=66 is nonsense and might even be dangerous on normal PC hardware,
> as simply the bus frequency is 33 MHz and nothing else!
> 
> How did you measure the speed boost? Please compare the speed at
> idebus=33 and with your setting of idebus=66 and post your values and
> how you measured the I/O speed values.
> 
> Alexander

To be clear once again: idebus=66 does NOT mean ATA 66 nor idebus=33
means ATA 33!

The UDMA setting is normally best self-detected by the kernel but can be
modified with "hdparm -X xx" (between the borders the hardware allows).

Alexander


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Alexander Dalloz | Enger, Germany
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