On Mar 12, 20:02, Russ Evans wrote:
> Subject: Re: A couple of questions re my problem...

> network, as Jules suggested; it was simply that the Syquest was causing
> the SCSI bus to hang (little yellow light on, Trev?  Corrupt file system
> on restart?).  At this stage, I'm looking to do a little clearing up of
> Mac disks on various machines, and to getr a -current kernel and sources
> inside a big partition here.  At that point, I might be able to do a
> little debugging (and I'll be coming back for help).  As I have a few
> ceilings to paint, this may not be until well into next weekend ...

I'm currently assuming that this is the same problem I'm having with a Zip
drive.

One test that I'd suggest you do right at the start, is to try writing to the
disk as a raw device.

e.g. dd if=/netbsd of=/dev/sd2c

I can do this 'till the cows come home, but when I have a file system on the
same partition, and mount it, and then try cp /vmunix /mnt, the system hangs
pretty solidly. I can't even get into the debugger. Yes, the little yellow
light is on. I did some experiments last night in regard to file sizes, and
found that it was OK to write reasonably small files, but that larger ones hung
the system. I should hopefully be able to quantify large and small fairly soon.
This occurs in single user mode, multi user mode with an idle console, and a
user over serial, and every other configuration I've tried. The hang is pretty
solid, mouse tracking stops in X, serial echo on a logged in tty stops, and I
can't even use the "programmers switch".

Can anyone suggest what I can do to get into the debugger on a IIsi when
commmand power doesn't work?

Anyway, if you find that you can reliably write to the raw device, but not to a
file system on the same device, you're getting the same symptoms as me, so I'll
be interested if you can get any further than I have so far in tracking this
mongrel down.

I'm working on the assumption that this is a file system problem, rather than
solely the fault of the SCSI driver.

Hmm, I've just remebered that I was planning on power cycling the Zip to break
out of the apparent deadlock, I must try that tonight.

Bernard.