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

Josef Möllers
2003-08-08T13:25:21Z

"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
-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html