The mongodump tool is a command-line tool that can make a backup of the data in our MongoDB cluster. As such, the downside is that all of the indexes need to be recreated on restore, which may be a time-consuming operation.

The major downside that the mongodump tool has is that in order to write data to the disk, it needs to bring data from the internal MongoDB storage to the memory first. This means that in the case of production clusters running under strain, mongodump will invalidate the data residing in the memory from the working set with the data that would not be residing in the memory under regular operations. This degrades the performance of our cluster.

On the plus side, when we use mongodump, we can continue taking writes in our cluster, and if we have a replica set, we can use the --oplog option to include the entries that occur during the mongodump operation in its output oplog.

If we go with that option, we need to use --oplogReplay when we use the mongorestore tool to restore our data back to the MongoDB cluster.

mongodump is a great tool for single-server deployments, but once we get to larger deployments, we should consider using different (and better planned) approaches to back up our data.