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

[Jeremy D Rogers]

On Mon, Jun 28, 2010 at 6:54 PM, Don Freeman <dfreeman at pagnet.org> wrote:
> 'Cuse me for jumping into the middle here.

By all means, jump in. I appreciate any and all ideas, and I should
thank Zack for the suggestion too (he may well be right), I just don't
*think* its hardware. But I suppose I better make absolutely sure.

> I presume you've considered bad/poorly formatted disks?

I had. I am using stamped data disks from conference proceedings right
now. I have two, one is DVD data and the other CD data. At some point
I verified that these CDROMs were actually working on another machine,
but I'll add that to the list of things to double check tomorrow. I've
also checked this across about 5-10 other disks although not recently.

> DVD's seem to be particularly sensitive to format/speed issues.

Right, tighter tolerances with smaller pits and all that. Which makes
it even stranger that DVDs are sometimes working and CDs not at all.
Not to mention that I am using pressed disks, not burned disks.

> 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?

So far, I've focused on reading disks that I know to be good assuming
that if I solve that, I should be able to burn and read burned disks
too. But I am not able to 'see' a blank CD for burning either. Since
reading DVDs sometimes works, I may try burning a DVD just to see if
that works.

> Some of the formatting techniques for CDs leave them unreadable
> without the software that formatted them.
> Are the sessions open or closed?

Again, I welcome all suggestions, but I especially would love to hear
from anyone who is familiar or has been keeping track of kernel
changes with regard to scsi emulation vs ata and that sort of thing. I
have a gut feeling it may be related to changes in the way CDROM
drives are handled at the kernel level, but again, maybe not.

Thanks, and keep any suggestions coming.
JDR

> 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
>>
>> _______________________________________________
>> Tucson Free Unix Group - tfug at tfug.org
>> Subscription Options:
>> http://www.tfug.org/mailman/listinfo/tfug_tfug.org
>>
>
> _______________________________________________
> Tucson Free Unix Group - tfug at tfug.org
> Subscription Options:
> http://www.tfug.org/mailman/listinfo/tfug_tfug.org
>
>
>
> _______________________________________________
> Tucson Free Unix Group - tfug at tfug.org
> Subscription Options:
> http://www.tfug.org/mailman/listinfo/tfug_tfug.org
>