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You can easily configure the time to declare a node as unavailable (dead) in your cluster setup. Since you didn't specify what clustering/high availability software you're using it's hard to tell you what to put in the config. In HeartBeat for example you can use:
# keepalive: how many seconds between heartbeats
# deadtime: seconds-to-declare-host-dead
to indicate when to move services and resources to the other node(s).
To what value you should set the parameters is up to you, if your services are business critical then you should set them low in order to have a higher disponibility meaning that if one node fails for that limited amount of time then the resources/services will be moved. You can also opt-out of failback, meaning that if resources/services are moved to another node, they will not be re-moved when the failing node becomes available again.