[T10] SBP 1394 hard drives hang with Windows XP (rare)

[Pat LaVarre]

* From the T10 Reflector (t10 at t10.org), posted by:
* "Pat LaVarre" <LAVARRE at iomega.com>
*
Great fun, thanks for sharing, no answers, some coments:
 
> I have written my own filter driver that limits the I/O size
> and the problem is resolved.
 
This filter driver actually changes nothing else?  It splits larger CDB's into smaller?  Or does it provoke Win PnP to limit the I/O size, thus changing much?

> ...
 
Apple hosts FireWire talk near sbp3 @ isg.apple.com, some of the posts there suggest 'send email to requests at isg.apple.com with subject "help"'.
 
In my personal history of pain, FireWire/IDE bridges failing qualification in this way would choke COMMONLY, Not rarely: like if we tried forty drives overnight we would see this issue once, guaranteed.  And if we chose to use an IDE drive we knew well we could force this kind of issue easily: all we had to do was make the drive error or hang.  Once upon a time, there was no bridge on the market that dealt well with that, and by and large the 13 cases heuristics were abysmally weak too.  Seems like many vendors don't bother to test all that.
 
The Win XP event log often had a copy of the raw hex of the offending "SBP2 Normative Annex B" CDB wrapper.  I forget the correct jargon for the name of that CDB wrapper, but I imagine you know what I mean.  The raw hex appeared unshifted, but in the middle of some other uncommented raw hex, so you might not notice it until after you grew accustomed to reading raw SBP2 hex.  Also Win XP events varied in whether they bothered to include such useful info.
 
I have heard rumours of a coordinated Apple/ Microsoft effort to let a 1394 device declare that it works best with a four-byte-aligned physical address, but I don't know anything more specific than that.
 
Pat LaVarre
 
P.S. I'm very glad to hear of people surmounting Microsoft's 64 KiB/ CDB barrier.  Wish more of Win could & did.  As life is, devices waste cost in reassembling streams pointlessly broken into multiple CDB's.

	-----Original Message----- 
	From: Mike Berhan [mailto:mikeb at bidali.com] 
	Sent: Fri 5/2/2003 8:48 AM 
	To: T10 at t10.org 
	Cc: 
	Subject: SBP 1394 hard drives hang with Windows XP (rare)
	
	

	* From the T10 Reflector (t10 at t10.org), posted by:
	* "Mike Berhan" <mikeb at bidali.com>
	*
	I am looking for some assistance from 1394 bridge chip vendors who may have
	knowledge about this problem (or anyone who can point me to a WEB site with
	specifics).
	
	I have experienced bus/device hangs on Windows XP with several 1394 hard
	drives from different vendors (you get that ugly "delayed write failure"
	error).  The hang occurs infrequently but I have narrowed it down to
	occurring during very large writes.  In one example, Windows was writing out
	3FFh sectors in a single I/O (~512K of data).  This is a valid request,
	though rare because you don't often see a request larger than 64K at a time
	in Windows.
	
	This could very well be a software issue, but I've experienced other
	problems with at least one 1394 bridge chip (in that case, it was problems
	dealing with odd aligned buffers).  My theory is that this is a bridge chip
	problem though I cannot say that definitively at this time.  I should note
	that I did install the "filter" driver that comes with the drive that is
	supposed to fix some sort of problem (what, I don't know, they don't
	specify).  However, that filter driver didn't fix anything for me.
	
	I have written my own filter driver that limits the I/O size and the problem
	is resolved.  However, before I make this filter driver available to others,
	I want to know exactly what this problem is.  Is it an I/O larger than 64K
	that has an issue?  128K?  256K?  Some scatter/gather limitation?  I thank
	you in advance for any information you can provide.  I also have this
	information passed into Microsoft as well.
	
	Thank you.
	
	Mike Berhan
	busTRACE Technologies
	
	
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