Howdy - What is the current best practice for migrating shards to another machine? I have heard suggestions that it is "add replica on new machine, wait for it to catch up, delete original replica on old machine". But I wanted to check to make sure...
And if that is the best method, two follow-up questions: 1. Is there a best practice for knowing when the new replica has "caught up" or do you just do a "*:*" query on both, compare counts, and call it a day when they are the same (or nearly so, since the slave replica might lag a little bit)? 2. When deleting the original (old) replica, since that one could be the leader, is the replica deletion done in a safe manner such that no documents will be lost (e.g. ones that were recently received by the leader and not yet synced over to the slave replica before the leader is deleted)? Thanks as always, Ian
