How to migrate a complete server and / or clients from old server to a new one?

Hi, am testing this on QNAP NAS, one thing we want to make sure is possible is able to move a client or at least all its backup data from an old to new server.

I notice there is a server key, i also see data folders for that client, but there is also a bulk loads of db files which i assume is for the UrBackup engine.

Is there a manual / docs for how to move the server / client data between servers?

Many Thanks