Summary

We plan to migrate our Mongo Atlas Sharded Cluster to a Mongo Atlas Replica Set in a different region and I was wondering what strategies people have used to do this. Also wondering if there was a way to do this with a little downtime.

Options I know of:

• Mongo Dump + Mongo Restore
  • Essentially we would have downtime throughout the whole process of Mongo Dump + Mongo Restore
• Use Zone Mapping to move all data from the 3 shards we have to 1 shard, then convert this to a replica set
  • Can be risky since if something goes wrong, our whole Mongo DB is basically down (we would have to recover using backups (but anything we miss, we would need to fix)
  • I believe downtime is required when removing the 2 shards + converting it to a Replica Set

Questions

• Has anyone migrated Mongo Atlas Sharded Cluster to a Mongo Atlas Replica Set?
  • What was the experience in doing so?
  • What method/strategy did you implement?
  • Did you have to deal with downtime, and how long?
  • How big was the Mongo Database?
  • What challenges did you run into doing this?
  • How long did the whole migration take?