Re: Redhat Upgrade Abortion - Again

From: Dave (shuvit_at_127.0.0.1)
Date: 10/08/03 

Date: Tue, 7 Oct 2003 20:45:36 -0700

"Paul Lutus" <nospam@nosite.zzz> wrote in message
news:vo6sohd761bbd5@corp.supernews.com...
 [...]
> PLEASE READ THIS CAREFULLY. YOUR SYSTEM IS HOSED. YOU NEED TO FIX YOUR
> SYSTEM BEFORE TRYING TO INSTALL LINUX, NOT AFTER.

Paul, I am sorry to see you getting so frustrated. And I wouldn't blame
you if you wanted to take a break, but I would miss your expertise.

I'm pretty sure the CD drive is not the problem. I've got the disk images
on my hard drive, and the md5sum's all match the ones you gave me. We don't
need the CD drive any more.

Just for curiosity, I tried a little "margin testing" on the CD drive to see
how far I could push it, and what the errors would look like. I drew a
single line with a magic marker across the entire data side of CD #2a. I
then ran 'linux mediacheck' ( PASSED ), md5sum (agreed with what we are
assuming is correct), and 'dd' (copied the entire image without complaint,
and the md5sum of the copy was correct).

Then I drew a second line across the disk. Same results. So I got one of
those wide magic markers and put a much thicker line across the disk (about
2mm wide). That did it!! The first thing I noticed after loading the disk
was that the orange "busy" indicator stayed on about 45 seconds intead of
the usual 15, and the green "DVD" light came on for maybe 10 seconds toward
the end of the 45. It usually does not come on at all.

I ran 'md5sum /dev/cdrom' and guess what. A whole screen full of repeated
error messages. Among the gibberish were some plain English words: [...]
Error: Not Ready [...] No reference position found (media may be upside
down). [...]

So my conclusion is the the drive is in good shape, that it will tolerate
media with defects much larger than the typical scratches we might expect,
and that the CRC mechanism is working well, able to fill in for fairly wide
gaps in the data.

Again, none of this matters, as we do now have *known good images* on the
hard disk.

Thanks again for your help.

-- Dave

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