Firewire Problems

[Richard Brown]

I have gone rounds with the Firewire problems in most flavors of OS X.

Your problem looks like the classic problem of earlier OS X, such as 
10.1.2, which was heavily discussed in Apple's own tech forums a while 
back. Turns out Apple left in a bizarre hardware shutdown command from 
which a Firewire drive can NOT awake without a restart.

Here is a repost of a similar issue AND FIX for same I once put on the 
Mac DV forum concerning a G4 and Firewire...

Apart from 5 internal drives in my G4, I have 15 ADS Firewire cases, 
usually with 8-12 online at any given time 24/7... I have every flavor 
of the ADS case since they started with Oxford chipsets. The best, by 
far, is the dual USB 2.0 - Firewire 400 external case, but sadly, it is 
MOST reliable under USB, not Firewire. Mac users are stuck, more or 
less, WITH Firewire. The beauty of the unit described is that it 
handles drives above 137 GB without issue, as in, can't wait for the 
Hitachi (formerly IBM) 400 GB units to ship.

Caveats:

1) The ADS cases (seldomly, but it happens) develop weird power supply 
issues, the net effect of which being it powers down drives, or cycles 
drives in a constant reboot cycle.  This can lock up OS X, up to 
10.3.3. Only ONE drive need have this problem to lock everything, and 
it can happen at, of course the worst possible moments.

2) If you are using older OS X, there is an OS issue, particularly back 
to 10.1.2, where a hardware shutdown command is issued from the OS to 
all external Firewire drives. If you see this behavior, and are 
frustrated from these lockups, the first thing you can do is: shut the 
Firewire drive down. It is not receiving or sending any data anyway, 
and it will not hurt data as a result. We did this a hundred times 
(easy) without issue, until an engineer and Unix guru (who discovered 
the anomaly) came up with a workaround: use the Terminal program, and 
issue the command:

sudo pmset -a spindown 0

This will tell OS X's  underlying Unix to NOT shutdown external 
Firewire drives. Works great, but WILL reveal if you suffer from No. 1, 
above.

Richard Brown


On Jul 25, 2004, at 10:20 PM, Mac OS X for Users wrote:

> (2) Often, the next time I go to mount this disk, even a day later, it 
> will
> not show up in the Finder, and/or Path Finder, and/or /Volumes.  The 
> only
> way to get it back seems to be to restart.
>
> Issue (1) is a minor annoyance, but issue (2) is a real pain.
>
> Have others experienced the same?  Can anyone explain to me why this 
> is a
> feature and not a bug?  Does anyone know if Apple is addressing this 
> issue?