[Linux-HA] 2 subnets separated by cisco 6509 switch

[Carson Gaspar]

--On Tuesday, March 15, 2005 13:33:05 -0700 Alan Robertson <alanr at unix.sh> 
wrote:

> What heartbeat relies on is reliable communication between nodes.  If you
> can have that, then you can be happy with it.
>
> Distance often makes that difficult.
>
> There are alternatives involving meatware stonith, but they're a bit more
> messy.

This really is a solved problem, but it does require a quorum mechanism. It 
should be practical to implement in heartbeat 2.x (now that it supports 
more than 2 nodes). Of course with a quorum mechanism, somebody looses 
badly in a site disaster with only 2 sites (one site or the other will have 
the tie-breaking quorum member - if the majority site goes boom, human 
intervention is required). But it does guarantee that split brain causes no 
harm, and is no worse that the current STONITH failure case (data center 
loss taking out server & STONITH device).

-- 
Carson