Regaining DMA capability of /dev/scdX drive

Slim Joe slimjoe2k8 at
Tue Oct 7 08:06:43 UTC 2008

On 2008/10/7, Eberhard Roloff <tuxebi at> wrote:
> Slim Joe wrote:
>> Is there a way to set the DMA on a drive that uses
>> IDE-SCSI emulation (/dev/scdX)?
>> Whenever I use cdparanoia to rip a physically bad
>> audio CD (e.g. with visible scratches), my CD/DVD drive
>> invariably loses its DMA functionality. This is obvious
>> from the slow reading of any later disk (data or video)
>> placed in the drive. The system as a whole also becomes
>> less responsive, a behavior which stops when I eject
>> the data or video DVD from the drive.
> Hi, just guessing. I had very similar behavior on a PC
> with two cd drives.  After much testing here and there,
> the trouble was gone after I clearly jumpered the drives
> to be Master and Slave.
> They had been "cable select".
> So you might check your PATA jumper settings.

Actually it's one of only two drives in my computer. The
other is a SATA hard disk. So I don't think your solution
applies in this case. This drive is rather old. But I do
now that in the past, I could reset the DMA on the drive
by using the "echo using_dma:1 > /proc/ide/hd[X]/settings"
trick. Now there's no /proc/ide/*/settings. So there's
nothing to reset.

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