DVD DMA Won't Stay On

crayiii · 10-02-2003, 03:31 PM

I have a DVD drive that Mandrake mounted at /mnt/cdrom2 and shows up as /dev/hde

When I enable DMA with hdparm -d1 /dev/hde and then do hdparp -d /dev/hde is shows DMA as enabled but when I access the drive it turned DMA off.

Does anyone know what could be causing this?

Ray

Thetargos · 10-03-2003, 12:06 PM

How did you eneble DMA, from a command line or from the rc.local init script?

I have set the SCSI-Emultion on my DVD and turned on DMA on rc.local with the standard /dev/hdd device. It works flawelessly. Hrere's how:

Pass the scsi emulation parameter to your kenrel. In GRUB you do so by just adding to the following to the first kernel line:
Code:
```
kernel /vmlinuz-<kernelversion> ro root=LABEL=/ vga=792 hdc=ide-scsi hdd=ide-scsi
```
Then you have to tell rc.local to add support for DMA for your drive. To so open in any text editor the file /etc/rc.d/rc.local and add this:
Code:
```
hdparm -d1 /dev/hdc /dev/hdd
```
Here I enabled DMA for both my cd-writer (/dev/hdc) and my DVD-Rom (/dev/hdd) drives
You will have to reboot for the changes in grub.conf to take effect and to start the SCSI emulation.

Hope this helps.

crayiii · 10-04-2003, 11:46 AM

Thank you for thei tips, unfortunately, it still doesn't work. I made the changes to lilo and ran lilo with no errors. After rebooting the drive still showed up as /dev/hde and not scd1 (my cd reader is scd0).

The DVD drive is running off of a maxtor ATA 100 controller card so I'm guessing this could be causing the problem.

Ray

kilgoretrout · 10-04-2003, 12:06 PM

Post your /etc/fstab file. When you change to scsi emulation you have to edit the cdrom line in fstab from /dev/hdx to /dev/scdx. Usually, the new hardware detection will pick up the scsi emalted drive on the first boot with it enabled and cofigure it for you, editing fstab. But if you ticked "Cancel" when the new hardware screen came up during boot, you'll have to edit it by hand.

crayiii · 10-04-2003, 12:33 PM

I made the change in fstab before I rebooted. Also, new hardware detection did not come up.

I'm thinking about getting a combo CDRW/DVD to replace both of my current drives and eliminate the Maxtor ATA 100 card today.