FreeBSD doesn't find my CD-RW and sometimes my DVD

[Andrew P. Lentvorski, Jr.]

On Fri, 25 Jul 2003, Lia Maggioni wrote:

> ACD0 is only the DVD , CD-RW (a Liteon 52x 24x 52x) isn't found at all!! 
> Literally from DMESG:
> 
> ata0-slave: ATA identify retries excedeed
> 
> and sometimes it doesn't find my DVD too , with the message :
> 
> ata1-slave: ATA identify retries excedeed

I would recommend setting the jumpers rather than using the cable select;  
it simply removes one variable from the problem.

Take the CD off of the same cable as your hard drive.  I would probably 
replace the DVD with the CD-RW to see if that works.  Then I would 
probably try to put the DVD and CD-RW on the same cable.

Check that your ATA cable doesn't violate the ATA specs (I think that 18" 
is the limit for an "in-spec" ATA cable.  Yes, that's *short*.)

I have been seeing this kind of intermittent problem with the ATA
subsystem since the ATA rewrite.  It has persisted into 5.1 Release. To be
fair, the failures are intermittent (read: really hard to debug), and I
haven't checked any of the old FreeBSD releases; so I am reluctant to
complain too loudly.

It seems that heterogeneous combinations of devices on the same cable give 
FreeBSD problems.  ie. a UDMA 100 and a PIO 4 device on the same cable.  
Normally this shows up as the slower device not being detected.  Putting 
slow devices on their own cable seems to cut down on the probability.

I presume that the issue is something along the lines of the chipsets in 
the slow device are slightly out of spec and the FreeBSD driver refusing 
to coddle broken hardware.  I am hesitant to blame FreeBSD as this may 
simply be a case of FreeBSD reporting the failure while other OS's simply 
degrade badly and hide the problem.

However, it is annoying as it's a complete crapshoot as to whether my ATA
CD-RW will be found on any given day.  I've tried 4 different
motherboards, 6 different types of cables, and 4 different CD-RW's.  All
of them exhibit some intermittent failures.

I'm really looking forward to Serial ATA.  Point to point connection 
should eliminate whole classes of this kind of breakage.

-a