Question

i was playing around on our dev server for a while for a new product and now it’s sorta live and i want to move existing data from a single machine (mongod, local) to our 6 server shard setup (2 shards each a 3 replica set) – is there any way to clone the db to a remote shard?

(worst case, a simple dump & insert with shard key example would be very nice!)

thanks!

Answer 1

You should add your dev server to the sharding environement :

• Restart your dev server with the –shard option
• on your mongos : type db.runCommand( { addshard : “serverhostname[:port]”, name : “migration” } );
• use the remove shard command to remove your shard “migration”.
• When it is done (you get “remove shard completed successfully”), you can stop your dev server and all your data have been migrated from dev to the new cluster

You don’t have to shard your database for the migration, however you need to do it if you want to benefit from sharding.

The advantages of this solution is that you have minimum action to take ( everything is automatic) and there is no downtime (the more load you put, however, the slower the operation is)
However this is a slow solution (slower than a manual copy).

One more advantage compared to raw files copy : the transfer will also compact (~ defrag) data, which is always good 🙂