Hard disk DMA Mode isn't working (using PIO)

**shebangs** · February 4th, 2010

Ubuntu Server 8.04.3 - 64bit

Two separate hard disks. If I put both disks in the following IDE configuration, DMA works on both disks as expected:

IDE0:0: HARD_DISK_20GB
IDE0:1: HARD_DISK_40GB
IDE1:0: empty
IDE1:1: empty

However, if I change it to the below config, it doesn't work. Only HARD_DISK_20GB has DMA, HARD_DISK_40GB uses PIO mode. This is really slow and usable.

IDE0:0: HARD_DISK_20GB
IDE0:1: empty
IDE1:0: HARD_DISK_40GB
IDE1:1: empty

I have added the following to /etc/modprobe.d/aliases

Code:

~# cat /etc/modprobe.d/aliases | tail -2
alias ata_generic off
alias pata_atiixp on
~# uname -a
Linux ez-greentrac 2.6.24-24-server #1 SMP Tue Jul 7 19:39:36 UTC 2009 x86_64 GNU/Linux

Info below:

Code:

~# dmesg | grep ata1.0
[   12.135067] ata1.00: ATA-0: Virtual HD, 1.1.0, max MWDMA2
[   12.135072] ata1.00: 41942880 sectors, multi 128: LBA 
[   12.138203] ata1.00: configured for MWDMA2
[   12.142940] ata1.00: configured for MWDMA2
# dmesg | grep ata2.0
[   12.304665] ata2.00: ATA-0: Virtual HD, 1.1.1, max MWDMA2
[   12.304670] ata2.00: 83884800 sectors, multi 128: LBA 
[   12.304678] ata2.00: simplex DMA is claimed by other device, disabling DMA
[   12.307473] ata2.00: configured for PIO4
[   12.309254] ata2.00: simplex DMA is claimed by other device, disabling DMA
[   12.312071] ata2.00: configured for PIO4

Any ideas please? This is really killing our Application.