Re: Summary of the Multi-Path BOF at OLS and future directions

["Josef Möllers" <josef.moellers@fujitsu-siemens.com>]

"jansen, frank" wrote:
> 
> > Josef Möllers wrote
> >
> > With MultiPath it _is_ necessary to TRESPASS a CLARiiON box if each SP
> > is conected to a seperate path.
> >
> To access the non-active path, this is correct.  What I was trying to say
> is that the MultiPath layer should be somewhat intelligent about this and
> be aware that there may be another active path.  It is much quicker to go
> down an active path than trespass a LUN and then do the I/O.  The other
> part is the risk of excessive trespassing, where a LUN just gets bounced
> back and forth between SPs for each I/O; this is an absolute worst case
> that would bring performance to a standstill.

Obviously.
What we did was to do a TRESPASS only if a command failed with certain
sense data:
ILLEGAL REQUEST, LUN NOT READY, CAUSE NOT REPORTABLE.

Have a nice weekend
-- 
Josef Möllers (Pinguinpfleger bei FSC)
	If failure had no penalty success would not be a prize
						-- T.  Pratchett
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