Re: 2.9test9-mm1 and DAO ATAPI cd-burning corrupt

From: Prakash K. Cheemplavam
Date: Wed Nov 05 2003 - 05:32:03 EST

Jens Axboe wrote:
On Wed, Nov 05 2003, Prakash K. Cheemplavam wrote:

Jens Axboe wrote:

On Wed, Nov 05 2003, Prakash K. Cheemplavam wrote:

Jens Axboe wrote:

On Wed, Nov 05 2003, Prakash K. Cheemplavam wrote:

Jens Axboe wrote:

On Wed, Nov 05 2003, Prakash K. Cheemplavam wrote:

Jens Axboe wrote:

On Mon, Nov 03 2003, Prakash K. Cheemplavam wrote:


well I am using k3b0.10.1 and either choosing cdrdao or cdrecord in

DAO mode to burn the cd ends up in non-bit identical copies, wheres ion TAO (atleast with my 10x CD-RW I tested) the copy succeded. I tried several times, and always got this issue.

bash-2.05b$ md5sum livecd-2.6_10-23-2003.iso
f73f3a74239dfe94b322b85fd14a306e livecd-2.6_10-23-2003.iso

bash-2.05b$ md5sum /dev/cdroms/cdrom1
f73f3a74239dfe94b322b85fd14a306e /dev/cdroms/cdrom1

bash-2.05b$ md5sum /dev/cdroms/cdrom1
09e7e2a51af4c64685831513fbac18c2 /dev/cdroms/cdrom1

Could you please try and cmp the two images, finding out how big the
corrupted chunks are and what kind of data they contain?

After some further investigation I found out, that the data is NOT corrupted, but in a way truncated in DAO mode: When I read out the image

from the CD-RW drive, about 5kbyte are missing at the end (and doing

several burn, it is always the same amount). Strange enough if I read the DAO burnt disk out by my DVD-ROM, the image can be read out completely! Can you understand this behaviour? I don't think it is a problem of my burner, but rather of the atapi driver?

Is actual data missing at the end? If yes, I'd say this looks a lot more
like a cdrecord problem.

Sorry, I wasn't precise: The data is on the disc, as my DVD-ROM restores the full image (md5sum matches), but the CD-RW does not.

You need to use the pad option to record.

Uhm, could you be more specific? I just use the k3b frontend to burn, and in the cdrdao manual I couldn't find something useful to it.

it's a cdrecord option, I've never used k3b so cannot comment on how to
make it enable that.

Hmm, I'll take a look, but I don't really think it is a problem of the recording programme, otherwise how could my reader read it out completely?

It isn't a problem of the recorder program. But some drives wont read
the very end of a disc unless there are some pad blocks at the end.
Thus, you should always use the cdrecord pad option.

Uhm, ok, I just took a look at the source image and the last (missing) 4096 bytes are just 00, so nothing critical missing your pad parameter sounds sensible. :) Should drop a note to the k3b devs then, as well...

> SG_IO or CDROM_SEND_PACKET? The latter should never have been merged in
cdrecord, and you should never use it. If it is using SG_IO, I'm very
interested in knowing more. vmstat 1 while doing the burn would be
interesting, just for 10 seconds where you see the problem.

Uhh, I'll try to find out. I must go now, but I'll report back later.

probably is a new issue. Furthermore my hd reading (I once contacted you because of that) didn't improve with the new kernel, though some bugfixes in this directions are mentioned by Andrew Morton.

Don't remember, sorry :)

I probably will make a new topic regarding issues (I think) I found with the new mm kernel.



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