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Re: "logical unit communication failure" c2scan NEC ND-4550A 1.07

Answering three messages in one, to keep the thread concise.

Joerg Schilling schrieb am 2006-02-12:

> Matthias Andree <matthias.andree@gmx.de> wrote:
> > >> status: 0x2 (CHECK CONDITION)
> > >> Sense Bytes: 70 00 04 00 00 00 00 0A 00 00 00 00 08 00 00 00
> > >> Sense Key: 0x4 Hardware Error, Segment 0
> > >> Sense Code: 0x08 Qual 0x00 (logical unit communication failure) Fru 0x0
> > >> Sense flags: Blk 0 (not valid)
> > >> resid: 123748
> > >> cmd finished after 6.422s timeout 40s
> > >> readcd: Success. Cannot read source disk
> > >> readcd: Retrying from sector 49.
> > >
> > > Did you try this on a platform that is known to work?
> >
> > I'm not interested in "known to work", but as the drive works with
> > FreeBSD 6-STABLE, is there a better way to isolate the problem than
> > running readcd with -v -V -d under strace(1) supervision?
> In case you don't understand "known to work", I refer to Operating systems
> that don't have SCSI related issues for a time that is long enough. I 
> currently know of two platforms that would fall into this category: MS-WIN
> and Solaris.

Did you understand my paragraph you quoted?
I'll take it apart for you:

1. I am not interested in your operating systems "known to work", and
   you know as much. Installing OSs may be your hobby, it's not one of mine.

2. I am not interested in hearing what OS you consider working anyways,
   since that changes daily.

3. FreeBSD 6-STABLE works for me. SUSE Linux 10.0 does not.

A few more comments:

4. you did not answer my question.

5. (no need to answer this because of 1 and 2) if you were aiming at a
technical definition of "known to work", you'd have to add MS-WIN and
Solaris versions and define "long enough".

> I have the impression that you are using Linux and Linux definitely 
> does not fall into this category (since ~ 2001, no SCSI bug I am aware of has
> been fixed in Linux). In case of unknown problems, it makes sense to change 
> things in order to find the reason.

Yes, Linux. Is the problem known to you? Did you file a bug report yet?
If so, I'll just quote the URL to the right parties.

> BTW: Did you run  FreeBSD 6-STABLE om exactly the same HW?

Is that a question or an insult?  Of course I did.

Joerg Schilling schrieb am 2006-02-12:

> This kind of problems have frequently been reported with Linux and Pioneer
> drives. These problems could be traced back to UDMA handling problems in Linux.

No Pioneer here, DMA state machine bugs still a candidate for culprit.

> As the problem is most likely DMA related, it still makes sense to boot
> SchilliX as he only needs to run readcd after a less than one minute boot
> from the Life CD.

Not interested. See assertion 3. above.

Joerg Schilling schrieb am 2006-02-12:

> Matthias Andree <matthias.andree@gmx.de> wrote:
> > > Change the UDMA mode to a lower setting and try again. Try a better 
> > > IDE cable and try again.
> >
> > As UDMA/33 works properly for everything else like growisofs reading or
> 80 or 40 wire cable?

I don't know, and I don't care, because it doesn't matter: the cable is
<45cm (I'm not buying longer ATA cables) and both devices are limited to
UDMA/33 by design.

> > writing a DVD (16X) or such, and FreeBSD (same computer, multi-boot)
> > manages -c2scan just fine with UDMA/33, I'd not look for hardware faults
> > here. It's rather an incompatibility between cdrecord and Linux or a
> > libscg or Linux bug.
> This bug is outside the scope of libscg.

That remains to be investigated.

Matthias Andree

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