knoppix dvd 5.0.1 boot error

[roleic]

hello,
while trying to boot knoppix dvd 5.01 I got the following error early during boot up:
"cannot unite read-only media and initial ramdisk"

I checked the md5sum which is ok.
I tried it on a Intel and a AMD box (both around 2.2GHz, 750MB RAM) getting the same error message.
Knoppix dvd 4 worked on both boxes just fine.
Searching in this forum I only found this error mentioned in the years 2004 and earlier for Knoppix3 and earlier saying things about patches. I don't think this still applies now.
Does anyone know how solve this problem?

[roleic]

I was able (forced;) to solve the problem myself.
It turned out that the DVD was not fully ok.
I reburnt one of the same make and same speed and then booting worked just fine.
It seems that the compressed file system of knoppix is very sensitive to the smallest discrepancies.
It would be wise not only to check the integrity of the initially downloaded iso-file as I did but also the actual burned DVD. However I am not sure how to check the md5sum for a DVD. Maybe someone has a hint on this.
Thanks.

[roleic]

When booting from the koppix dvd you can find in the grub menu under F2 a special cheat code for testing the knoppix dvd.
This feature is really recommended after burning since even small errors have drastic effects.

[roleic]

there is another more general way to verify a cd / dvd with its original iso-file after burning:
create md5sum of the iso-file:

md5sum ORIGINAL-ISO-FILE.iso

read cd/dvd from eg. /dev/hdc and take only the initial portion of the same length as the iso-file leaving away the lead-out at the end and then send this into md5sum:

dd if=/dev/hdc | head --bytes $(stat --format=%s ORIGINAL-ISO-FILE.iso) | md5sum

Now compare the two md5sums. If they are the same you have a good burn.
I was surprised how many bad burns I produced without even knowing. Just a fingerprint can ruine your burning.
In case of music or video data you will not recognise the flaws. However, the compressed file systems like those of Knoppix will not forgive the slightest flaw.

[benx009]

you pretty much took care of everything yourself here. i'm sure the info will be valuable to whoever will later need it.