Re: [ofa-general][PATCH 3/4] SRP fail-over faster

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Thu, Oct 15, 2009 at 03:25:15PM -0400, David Dillow wrote:
> On Thu, 2009-10-15 at 09:23 -0700, Vu Pham wrote:
> > David Dillow wrote:
> > > And if I want to disable this completely?
> > >   
> > 
> > Unless these patches are bad and affect the stability of the driver, why 
> > do you want to disable it? If you don't use multipath/device-mapper and 
> > use /dev/sd**, everything will be  same
> 
> I use multipath with ALUA, and I don't mind if the link flaps a bit. 60
> seconds is near my SCSI timeout of 77 seconds, so it doesn't buy me
> much. I'd rather multipath be delivering traffic to the backup path than
> sitting on its thumbs for 60 seconds doing nothing.

I've been left with a similar impression for several multipath things
I've seen in the past. True active/active multipath setups should have
a shorter timeout - there is no penalty for directing more traffic to
the 2nd path (the paths should be load balancing existing traffic in
the standard case anyhow).

An active/passive configuration might be different...

Certainly an enforced lower limit in the kernel is silly, and a
per-device setting does make some sense.

Jason
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