Quartz clustering setup when running in tomcat on multiple machines

Question

I have a webapp which will run on 2 different machines. From the webapp it is possible to "order" jobs to be executed at specific times by quartz. quartz is running inside the webapp. Thus quartz is running on each of the two machines. I am using JDBC datastore to persist the jobs, triggers etc.

However, the idea is that only one of the machines will run jobs and the other will only use quartz to schedule jobs. Thus, the scheduler will only be started (scheduler.start()) on one of the machines.

In the documentation it says

Never run clustering on separate machines, unless their clocks are synchronized using some form of time-sync service (daemon) that runs very regularly (the clocks must be within a second of each other). See http://www.boulder.nist.gov/timefreq/service/its.htm if you are unfamiliar with how to do this.

Never start (scheduler.start()) a non-clustered instance against the same set of database tables that any other instance is running (start()ed) against. You may get serious data corruption, and will definitely experience erratic behavior.

And i'm not sure that the two machines in which my webapp is running have their clocks synchronized.

My question is this: Should i still run quartz in clustering mode for this setup when only one of the quartz instances will be started and run jobs while the other instance will only used for scheduling jobs to be executed by the first instance.

Answer 1

What about simply starting the scheduler on one node only and accessing it remotely on another machine? You can schedule jobs using RMI/JMX. Or you can use a RemoteScheduler adapter.

Basically instead of having two clustered schedulers where one is working and another one is only accessing the shared database you have only a single scheduler ( server ) and you access it from another machine, scheduling and monitoring jobs via API.

Answer 2

If you will never call the start() method on the second node, then you shouldn't need to worry about clock synchronization.

However you will want to set the isClustered config prop to true to make sure that table-based locking is used when data is inserted/updated/deleted by both nodes.