If the client is keen to keep costs down... and is amenable to it... then you could give him an alternative URL to use in the case of a catastrophic failure (i.

If the client is keen to keep costs down... and is amenable to it... then you could give him an alternative URL to use in the case of a catastrophic failure (i.e. your plane scenario). Then it's up to you if you use two haproxies for active-active or just maintain two active-passive sites.