> Date: Wed, 15 Jun 2011 18:04:24 +1000 > From: David Gwynne <l...@animata.net> > > the subject line says it all, but happy to explain further if > required.
Hmm, I'm somewhat confused: > +#define MPATH_ROUNDROBIN 0 > +#define MPATH_NEXT MPATH_ROUNDROBIN > +#define MPATH_LRU 1 What does MPATH_NEXT mean? Is that the strategy you fall back on if the path you're using fails? What if you have more than 4 paths to a disk with a device that only allows a single active path and one of them fails? Are you suddenly going to try roundrobin scheduling of IOs? Also, I don't quite understand what MPATH_LRU would mean. Least Recently Used? How is that different from Round Robin? Don't you need a Last Used policy for devices that can only have a single active path or devices where there is a significant overhead for switching to a different path.
