Re: Is there a grand plan for FC failover?

Philip R. Auld
2004-01-29T14:51:37Z

Rumor has it that on Wed, Jan 28, 2004 at 05:16:51PM -0500 James Bottomley said:
> On Wed, 2004-01-28 at 16:02, Smart, James wrote:
> > I'd add one additional issue :
> >
> > 3) SCSI Reservations
> >
> > I guess this could be considered a part of (2), but given that reservations
> > bring in a host of additional problems, and potentially brings up multi-host
> > configs/clusters as well...
>
> The current crop of cluster implementations that use reservations manage
> quite well in user space alone. Certainly, though, the presence of
> reservations can interfere with failover code and may be considered a
> problem that needs to be solved in multi-path...it all depends on how
> the multi-path devices react to path switching in the face of
> reservations.
>

It needs to be known to the pathing layer if you've got load balancing.
It has to know which path has the reservation and only use that one.

> I'm open to suggestions on this, but I think it should be done
> separately as part of a device ownership API.
>
> James
>

--
Philip R. Auld, Ph.D. Egenera, Inc.
Principal Software Engineer 165 Forest St.
(508) 858-2628 Marlboro, MA 01752