Setting up MongoDB to work with two data directories

You can use the directoryperdb configuration option so that each database's files are stored in a separate subdirectory, and then use different mount points depending on the volume you want to use.

This option can be helpful in provisioning additional storage or different storage configurations depending on the database usage (i.e. SSD or PIOPS for a database which is more I/O intensive, while using normal EBS storage for archival data).

Important caveats:

• There is a highlighted note in the documentation for directoryperdb which shows how to migrate the files for an existing deployment.

• If you separate your data files onto multiple volumes, this may change your Backup Strategy. In particular, if you are using filesystem/EC2 snapshots to get a consistent backup of a running mongod you can no longer do so if the data and/or journal files are on different volumes.