Hi @Stuart_S
For live data migration, you need to convert the stand alone replica set to a single node replica set and then pull the data to Atlas.
Please note that, as per the documentation, you cannot user M0/M2/M5 shared tier clusters as source or destination for live migration.
To add more details to the above information,
- If your data size is large, you can resync the replica set member to speed up the process.
- If you wish to move data to Atlas, you can follow the documentation for the same.
Please note that, the process can potentially be disruptive, hence the recommendation is to test the workload before performing on the production environment.
Let us know of you have further questions.
Best Regards
Aasawari