[CentOS] Re: DMA mode

Paul Schoonderwoerd paul at pollux-it.nl
Tue Jun 3 08:54:56 UTC 2008

On Tuesday 03 June 2008 10:17, Tom G. Christensen wrote:
> David Mackintosh wrote:
> > Hi folks,
> >
> > I have an HP Proliant 140DL G2 server with what appears to be an IDE
> > drive in non-DMA mode.  Performance on the server is extremely bad
> > when large amounts of disk activity is taking place.
> >
> > I think the problem is that my drive is not in DMA mode:
> >
> > # hdparm /dev/hda
> This should be /dev/sda and not /dev/hda which means you're most likely
> using the generic-ide driver and not ata-piix.
> Google suggests booting with ide0=noprobe ide1=noprobe to make sure the
> ata-piix driver is used.
> If you don't want to reinstall then make sure initrd contains the
> ata-piix driver and that references to /dev/hd* are replaced with
> /dev/sd* in fstab etc.
> -tgc

Timing is everything !
I found the exact same problem on a HP Proliant ML110 at the exact time I read 
Adding the ide0=noprobe to grub.conf instantly solved the problem. fstab 
picked it up itself without any changes and the disks now show up as sda. The 
'hdparm -t <disk> went from 3.6 MB/s with /devhda to 76MB/s with /dev/sda.

This would be a good one for the wiki. (or maybe it's already there, didn't 

So thanks Tom for you answer. Greatly apreciated (here also).


Paul Schoonderwoerd
Pollux IT

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