Is there any easy way in Ignite to persist to disk after the Ignite servers are up and running and filled in with data?
I have seen https://apacheignite.readme.io/docs/distributed-persistent-store#section-usage but it seems you need to supply the XML property at startup of your Ignite topology in order to persist to disk.
There's no easy way I can think of. You will need to start new nodes, with persistent data region, and somehow transfer data to those nodes to newly created persistent caches. The easiest way will be to create them as a part of new cluster.