burncd ``only wrote -1...'' coasting discs.

[Lowell Gilbert]

Lewis Thompson <purple at lewiz.net> writes:

> I'm trying to use burncd to write an ISO to a blank disc.  The discs are
> all fine, etc. and this is a new DVD drive (writes DVDs and CDs), so I'm
> guessing that is the problem.

By itself, it shouldn't be.  If you're running 5.x, that's another
story (the relevant code has gone through a whole series of
significant changes there), but since you didn't mention what your OS
configuration was like, I'll assume you're running a "production"
release of the OS (4.x).

>   A simple output is as follows:
> 
> lewiz at black /mnt/packages/unix/isos/hurd > sudo burncd -s max -f
> /dev/acd0 data disc1.iso fixate
> next writeable LBA 0
> writing from file disc1.iso size 646272 KB
> written this track 832 KB (0%) total 832 KB
> only wrote -1 of 32768 bytes: Device busy
> 
> fixating CD, please wait..
> lewiz at black /mnt/packages/unix/isos/hurd >
> 
>   This leaves me a bit annoyed but with a shiny new mat for my glass.
> Problem is I have quite a collection now and I'll have to start handing
> them out to my friends soon.

I tend to recommend using CD-RW disks for experimenting instead of
CD-Rs.  They tend to require much lower speeds, which can hide some
kinds of problems, but at least you can rule out a number of areas.

>   I'm wondering if it's because the drive doesn't have BurnProof (or
> similar)?  It's a fairly hi-spec machine (XP2800) and the CPU usage at
> the time was around 4%.

BurnProof shouldn't be relevant.  I don't think burncd will use it
anyway, although I'm too lazy to actually check the code.  With a
*really* fast burner, I suppose it's possible that your system can't
the data off the hard disk fast enough (particularly if the image is
mounted over a network, as seems to be the case from your directory
path), then buffer underruns are definitely possible.

The first thing to look at is whether it works at a lower speed.  In
fact, start with a burn speed of 1x or 2x.  If that works, then the
media you're using can't handle the top speed of the drive.  This is
quite common these days.  If underruns are occurring, then burning at
a slower speed should avoid the problem as well.