Logstash Exceptionhandling/Failover for output plugins

We are currently evaluating ELK and so far it looks very promising, but we found one big issue we couldn't find satisfying information so far:

We want to log all our events in Elasticsearch, so when something fails there, we want to implement some kind of failover mechanism and save the according data somewhere else, so the basic question is:

How can we catch Exceptions from an output plugin and handle them? I already discussed this and it seems there is no general solution for such cases so far. What we would need is something like:

output {
elasticsearch {
...
}
failover {
file { ...}
}

or:

output {
failover {
elasticsearch {
...
}
file { ...}
}
}

As I mentioned above, for us this is a really important issue and my prevent us from using the ELK stack if we don't find a solution for that problem...