[X-Unix] Re-mounting a Firewire Disk

[William H. Magill]

On 10 Jan, 2005, at 00:16, Jerry Krinock wrote:
> To avoid forgetting to pull the plug without ejecting a firewire disk,  
> I
> have a script which ejects it every day.  But sometimes I don't leave  
> and
> want it mounted again.  So, I have to pull the plug, count to three,  
> and the
> plug it back in.
>
> This is so annoyingly silly.  I've been playing with diskutil trying  
> to find
> a less labor-intensive way of doing this, but can't find any.  Is  
> there a
> way?

It has to do with the design philosophy of the bus -- it really is  
oriented around "PLUG and play!"

I believe that the dismount operation will cause the FireWire drive to  
spin down and go quiescent.

Once it has gone quiescent, I would assume that the drive is no longer  
listening on the data portion of the bus, and that it requires an  
interrupt (bus reset) on the signal portion of the bus to "wake up" and  
again listen.

Probably a "firewire bus reset" is needed, but I don't know for certain.
I found a reference in the Apple lists archive from Feburary 2004:

"Look at the function "BusReset" in IOFireWireLIb.h.

  However, instead of using BusResets to reset the whole system, use an
  analyzer (FireBug or FireSpy) to see what is really going on."

(Both FireBug and FireSPy are in the firewire SDK. Weather either is  
easier or faster than simply unplugging and replugging the connector is  
problematic.)

http://lists.apple.com/archives/firewire/2003/May/msg00013.html

http://developer.apple.com/documentation/DeviceDrivers/Conceptual/ 
WorkingWFireWireDI/FWDevInterfaces/chapter_1_section_2.html

T.T.F.N.
William H. Magill
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