Gitter's MongoDB data is stored on EBS volumes formatted with XFS. This combo means that we can resize a volume online, without even stopping the mongod process. This is how it's done.
- Increase the size of the EBS volume. You can safely ignore the warning messages about resizing it: we'll do this later. This process is the longest part of the operation. Just wait for the resize to complete.
- Once the volume has been successfully resized, log onto the MongoDB node that you want to resize and run
sudo xfs_growfs /var/lib/mongodb. - You're done. No, for real: you can log out and do something else.