Looking for way to monitor dsync, confirm it is or isn't running

I am syncing two Dovecot sites using the dsync function.

I would like to be able to run some sort of periodic health check to confirm that dsync is (or is not) running properly between the two sites, and alert me if dsync is failing or lagging excessively.

Does anyone know of a tool to do this? (If possible, something I can set up to run periodically in Nagios?)

Thanks for any suggestions.

Rich Wales richw@richw.org