[Tfug] CDs: no medium found, DVDs work (sometimes)

[Don Freeman]

'Cuse me for jumping into the middle here.
I presume you've considered bad/poorly formatted disks?
DVD's seem to be particularly sensitive to format/speed issues.
Some of the newer formats don't work on the older drives.
What are the CD formats you are having trouble with? 
Have they been formatted as RW's? 
Some of the formatting techniques for CDs leave them unreadable 
without the software that formatted them.
Are the sessions open or closed?
Etc.

-----Original Message-----
From: tfug-bounces at tfug.org [mailto:tfug-bounces at tfug.org] On Behalf Of
Jeremy D Rogers
Sent: Monday, June 28, 2010 4:37 PM
To: Tucson Free Unix Group
Subject: Re: [Tfug] CDs: no medium found, DVDs work (sometimes)

On Mon, Jun 28, 2010 at 6:16 PM, Zack Williams <zdwzdw at gmail.com> wrote:
>> I can rule out hardware for 2 reasons: all three systems consistently
>> fail to read CDs. DVD's seem to mount ok 'sometimes' - maybe 1/2-2/3
>> of the time.
>
> DVD's and CD's have a different focal length to the disk from the read
> head, so it's quite possible that a drive will be able to read one but
> not the other.   This is relatively common - I think you have bad
> drives.

Not only different focal lengths, but different lasers altogether from
what I understand.

 I would entertain the idea that this is a bad drive if all I had were
a single system failing, but it seems extremely unlikely given that
all three systems failed, and even more unlikely that they all failed
around the same time. I'm pretty convinced this is software.

I am tempted to try pulling a drive and sticking it in a windows
machine, but these workstations get heavy remote use, and I don't want
to reboot and have them down much. Maybe it's the only way. I may
check that tomorrow.

But in the meantime if anyone has any ideas on anything to check for,
I'd love to hear them. I once saw something about how dvd mounting is
different from CD mounting in ubuntu with regard to something like hal
or udev or some policy somewhere. That may or may not be a lead, since
the different seems to be pretty low level, but I can't seam to find
the right words to get google to understand what I only vaguely
remember seeing once.

>
> Not worth spending the time to debug when you can buy a replacement for
<$30.

Unless this IS a software issue and $30 (x3 = 80-100+shipping) becomes
money poorly spent.

> - Zack
>
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