We have used Redhat server cluster on a project. It is pricey but does all the heavy lifting.
If you do not want to pay for Redhat then I know heartbeat can be setup to work if you want it for no money. To resolve the var issue if you can, stretch to back end fibre storage that normally does the trick and is lovely and fast. Failing that a Crossover Gig cable into the nics can get you some of the way then you can rsync or mount an NFS location.
Tony
Tony Wood : twitter.com/tonywood
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