Arran Cudbard-Bell wrote:
Alan; I'd be interested in hearing what the 'corner cases' are where fail-over is advantageous.
When you're too lazy to write your own solution, *or* where you've never run into problems with the protocol.
It depends how seamless you want to make the fail-over process. You don't have to run truly clustered SQL, you can get away with a Master-> Slaves type arrangement. With MySQL at least, it's possible to nominate one of the replicas as a new master should the current master fail; this process can be automated to a large degree. Fail-back is much harder (apparently), and would be difficult to automate.
Having active/active servers assign leases "live" from the same pool would be nice, too. That's only slightly harder to do. Alan DeKok.