Re: Self-written DVD+Rs that cannot be read...

[Seth Kurtzberg <seth@cql.com>]

Hugo van der Merwe wrote:

On Sun, Feb 20, 2005 at 11:48:37PM -0700, Seth Kurtzberg wrote:
  

Did you answer my previous question about whether the drive supports 
DVD+R and DVD-R, or just one of the two?
    

The drive is definately supposed to support "everything". DVD+R and 
DVD-R...

To answer all your questions: The drive is a BTC DVD±R/RW 16x Writer,
says the box. Using Debian GNU/Linux, sid/unstable. I can read most of
the data from the DVD+R on the writer. My normal DVD-ROM drive struggles
with the DVD+R - think it *might* be more capable of DVD-R? I am writing
DVDs with photos for other people to read in their DVD-ROM drives, this
stuff needs to be "compatible"...

I know other people struggle with the DVDs in Windows. I have heard that
some can read most of the photos, but not all of them, sounds like the
writing process failed somewhere. I've had other reports of "does not
work", this might be the same, or might be that their drives cannot read
the DVD+R's at all, who knows.

I could try scsi emulation (I've tried using that to try dvdrecord -
dvdrecord failed with some scsi error...), I am thinking that software
is not the problem though. The drive is writing, if I write only 500MB
to the DVD, I'll probably have more than 80% of them being successfully
written and then read. (This is a guess based on where the thing starts
failing when reading.)

I will let you know how other media works out for me. Firmware problem 
due to the drive not obeying -speed=1?

Of course it isn't possible to say anything with 100% confidence.  (Well, it isn't possible to say anything with 100% confidence and actually be correct  :)  .)

If the drive is supposed to support writing in 1x mode and in fact doesn't, that is suggestive of a firmware issue.  (Nothing in this area is going to be more than suggestive.)  It may actually write at 1x although it doesn't report that it is doing so.  In that case I wouldn't be surprised to see -speed=1 make things worse.

The first thing one thinks of with these sorts of errors is that the machine is having a problem making sure that the buffer is never empty.  I believe you said earlier that you don't have access to those messages?  Is there a way to turn them on, or provoke increased verbosity, or increased logging verbosity (or any damn thing that gets you more information)?  It's easy to speculate, but some nice, solid information is always better than any speculation.

It might be interesting to try the version limited to 1gig writes, and see if the results still match what you observe (errors after about 500 MB).

 Do I then need to take the drive 
to a windows machine in order to do the firmware update? Bothersome. 
Suppose it needs to be done.
  

The common procedure is to have a bootable MS-DOS disk used to change firmware, since it can't ordinarily be done in protected mode.  With a bootable floppy (or a bootable CD, for that matter, using Syslinux in floppy emulation mode) you shouldn't have to physically move the drive.

It is possible in certain situations and certain kernel options enabled, to rewrite firmware from Linux, but given that this is a problem you are trying to solve, rather than a routine operation, it might be better to avoid mixing up two things that are bleeding edge.

Thanks a lot,
Hugo

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