drive buffer underrun = disk not trustworthy?

ctos · 03-24-2006, 05:16 PM

If I get a buffer underrun indication, should the CD be thrown away? Does the error mean that there is definitely something missing from somewhere on the resulting CD?

Code:

"Total of 2 possible drive buffer underruns predicted."

command used:

Code:

cdrecord -v -dev=ATAPI:0,0 -speed=0 ~ctos/file.iso

Sometimes it works without any underruns. I have used -speed=8 also. I get consistent success when I specify 8 and leave the computer alone. I'm not a disk-burning industry so I don't mind much. Perhaps at some point I'll try to get DMA into the kernel:

Code:

Warning: Using ATA Packet interface.
Warning: The related Linux kernel interface code seems to be unmaintained.
Warning: There is absolutely NO DMA, operations thus are slow.

But I just want to clarify that the underruns mean the CD should be used as a coaster or Christmas tree ornament, correct?

By the way in case any fellow newbies happen along this post at some point, looking for a way to burn bootable ISOs with no fanfare, the above works. You might need something other than "ATAPI", and perhaps use a different speed (such as "8"). I tried using K3b and got bad results. As my userid, I couldn't get it to burn. When I ran it as root, it still wouldn't burn, but it made the CDROM go faster than I've ever heard it.

tuxdev · 03-24-2006, 05:32 PM

Because the drive can't just use DMA to grab the data itself, it needs to depend on the processor to give what it wants. When your processor is too overloaded to give the data the CD wants, it underruns. Fix it by activating DMA or leaving it alone to do its job properly. The CD burnt should be reburnt if possible, tested throughly, or used as a coaster.

Jeebizz · 03-24-2006, 05:37 PM

Why can't DMA be used at all?

ctos · 03-24-2006, 09:08 PM

I think I haven't put into the kernel. I haven't solved that one yet. At least I can burn 'em!