Slow DVD burning and problem with DMA

NathanZachary · Moderator Joined: 30 Jan 2007 Posts: 2609

Hello all,

I was burning a data DVD this evening using k3b and realised that it was only burning at ~1.4x instead of the declared 4x. The media I'm using is fine and capable of 4x. My CD burner and DVD burner are set to /dev/hda and /dev/hdb respectively. However, when I looked at the hdparm, both currently have DMA disabled. I naturally suspected this to be the problem. However, when I try to enable DMA, I get an error that the operation is not allowed. Does anyone have a suggestion? Am I right to assume that the slowness is most likely caused by DMA being disabled, or is there another area into which I should investigate?

Thanks preemptively.
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“Truth, like infinity, is to be forever approached but never reached.” --Jean Ayres (1972)
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yabbadabbadont · Posted: Tue Oct 28, 2008 3:52 am Post subject:

Since they are hda and hdb, then that means that one of them is set as a slave to the other. I've had problems in the past with that type of setup. I've found that it works better to keep them on separate controllers if possible, even if it means that both drives end up as slaves to hard drives.

Alternatively, if it usually works at 4x, but only sometimes burns slower, then I would guess that you might have previously mounted/burned to RW media. I found that my drive will refuse to burn DVD+R at 8x if I've had RW media in the drive prior to the attempt during that same boot session. (it takes a full system reset to restore full speed burning)

NathanZachary · Moderator Joined: 30 Jan 2007 Posts: 2609

Thanks for the information. However, I can't put them on separate controllers as there is only one PATA controller on my motherboard, and my HDD is SATA. Also, I haven't used any RW media, and it always burns at around 1.4x instead of the full speed. Again, thanks for the suggestions though.

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“Truth, like infinity, is to be forever approached but never reached.” --Jean Ayres (1972)
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yabbadabbadont · Posted: Tue Oct 28, 2008 4:03 am Post subject:

Just running down all the things that have screwed me over in the past.

How about removing one of the drives temporarily so that there is only a master on the controller? Should be a quick operation. Just unplug the power to the slave drive. I'm guessing that the DVD burner is the master drive on the cable.

NathanZachary · Moderator Joined: 30 Jan 2007 Posts: 2609

Actually, I'm a moron. After my previous motherboard failed on this computer, I got one that has two PATA controllers. I have never had anything on the second controller, so what will the devices show as instead of /dev/hda and /dev/hdb? Also, I have them listed as /dev/cdrom and /dev/cdrom1 in my /etc/fstab.
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“Truth, like infinity, is to be forever approached but never reached.” --Jean Ayres (1972)
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yabbadabbadont · Posted: Tue Oct 28, 2008 4:19 am Post subject:

They should be hda and hdc. You'll need to remove or modify /etc/udev/rules.d/70-persistent-cd.rules after you move one of the drives.

NathanZachary · Moderator Joined: 30 Jan 2007 Posts: 2609

Thanks for the information. I will just unplug one of the drives temporarily and see if the problem goes away before messing with any of the udev rules. Any idea what could be causing the DMA issue though? I will post the exact error message when I get home from work.
_________________
“Truth, like infinity, is to be forever approached but never reached.” --Jean Ayres (1972)
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yabbadabbadont · Posted: Tue Oct 28, 2008 6:12 am Post subject:

I think that I ran into the DMA issue whenever I had two optical drives on the same controller. Of course, you should check your BIOS settings to be sure that DMA is enabled there and that you have DMA support enabled in your kernel.