Auto snapshot catchup

[bdrewery]

If the server, or cron, is down during an infrequent snapshot interval, a snapshot may be missed. For example, if yearly is being used, there's a chance that this snapshot will be missed if the 1 time it tries to do it, the pool is down, or cron is down.

The script should run more often and be smarter about when to create new snapshots per interval.

[szenti]

I think it's not the script's task to handle missing executions. Anacron is made for this kind of scheduling.