Hot Standby Hot Standby

[Stephen Nelson-Smith]

Following on from testing yesterday, I can't see a way to do this:

* Traffic ---> backend1

* backend1 fails

* Traffic ---> backend2 (hot standby)

* backend2 fails

* Traffic ---> backend3 (2nd hot standby)

ie we cannot have a hot-standby-hot-standby.

The best I have come up with is weighting the two backup backends, so
only a very small amount of traffic goes to one of the two live backup
machines.  This isn't ideal - the spec I need  to meet is to have two
tiers of failover, with the app only ever running on a single
instance.

How can I achieve this?  Is it possible?

S.