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Re: DMA on DVD/RW Inspiron 6000

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  • J.Daniel Christensen
    ... I figured out how to get the higher speed. My DVD drive is a SATA device, so the key is to get libata to handle it, rather than the ide layer. It turns
    Message 1 of 3 , Nov 27, 2005
      Dan Christensen <jdc@...> writes:

      > garry191 <garry191@...> writes:
      >
      >> Hi Guys, dd access to my DVD drive on Inspiron 6000 is very slow.
      >> hdparm informs me that DMA is not supported on this device. Any tweaks
      >> to make the DVD faster?
      >
      > I'm struggling with a similar issue on a Latitude D810 right now. The
      > good news is that with Ubuntu's 2.6.12 kernel, the dvd drive is at
      > /dev/scd0 and the access is just fast enough that I can watch a dvd
      > (hdparm reports 2.2 MB/s). I believe this is without dma, which
      > I can't enable.
      >
      > The bad news is that with a self-compiled 2.6.14.2 kernel (with a very
      > different .config), I tried ide-cd, so the drive appeared as /dev/hdc,
      > and I only got 1.56 MB/s, and my dvd player stuttered. With ide-scsi,
      > the drive appeared as /dev/sr0, and I only got 1.2 MB/s. Any
      > suggestions for how to mimick the Ubuntu kernel's performance?

      I figured out how to get the higher speed. My DVD drive is a
      SATA device, so the key is to get libata to handle it, rather
      than the ide layer.

      It turns out that Ubuntu's kernel contains a patch to 2.6.12 which
      turns on libata's handling of ATAPI devices. In 2.6.14.2, this is
      controlled by a module option. If you have libata compiled in, it is
      libata.atapi_enabled=1
      on the boot command line. If libata is a module, you want
      options libata atapi_enabled=1
      in a file in /etc/modprobe.d. (In my case, I had to put such a
      file in the initrd since the module is loaded before the filesystem
      is mounted.)

      Not sure if this will help the original poster, but it may help
      others with SATA DVD drives.

      Dan
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