K3B - how to burn an ISO-CD without errors?

[alan c]

Bas Roufs wrote:
> Dear Everybody
> 
> Tonight, I downloaded a fresh Kubuntu 8.10 i.386 ISO image - with a
> view to burning it on a CD for installation on a laptop. After
> downloading the image file, I opened it with K3B - running on a
> desktop PC with Kubuntu 8.10. I carried out the MD5SUM check via K3B
> and this page:
> https://help.ubuntu.com/community/UbuntuHashes
> The MD5SUM check went perfectly well. Than, I put an empty CD in the
> tray and started the burning process. I simply chose for standard
> options:
> * automatic speed, etc. K3B chose 16 speed for the process.
> * for the 'writing mode' I chose 'auto', instead of 'DAO', 'TAO' or 'RAW'.
> * I also chose the option 'verify written data'.

k3b 'verify' has not worked recently, not sure about kubuntu 8.10 
though. I use an independent md5sum activity now.

> After the end of the burning process, everything seemed OK.
> So, I put the CD in the CD/ DVD combodrive of the laptop and I tried
> to start the install process. After about 10 minutes the installation
> process ended up in a big mess. So, I restarted the CD and carried out
> the 'integrity check': there were mistakes in 33 files. So, something
> must have gone wrong in the burning process.

I would expect an md5sum type of check would give a similar result to 
a cd self verify check. However, in one machine I was amazed that I 
got very inconsistent results. I did many tests and concluded that the 
machine which had been donated to me, had a fairly small power supply 
capacity, and the power suppluy was falling below requirements on some 
occasions - during install there is a lot of CD drive activity and 
also HD activity  so the PSU is stressed.

The PC had been purchased with one cd rom drive. Later a CD RW drive 
was also fitted and took  more power. When I removed the CDRW drive, 
all results were consistent and good. I would have fitted a more 
powerful PSU however it was a very special size in that particular 
(Dell) model.

On other projects I found I had unknowingly purchased 100 CD blanks 
which were very poor quality. I needed a lot of burning. I checked 
most CDs after burn. Nearly 30 % were failed on md5sum checks. They 
would probably have been ok for some other cd activities, audio etc, 
but not for iso image burn, which needs to be bit perfect afaik.

Burning at an even slower speed did help a bit but the main trouble 
then was a poor batch of CDs.

good luck
-- 
alan cocks
Ubuntu user #10391
Linux user #360648