The --w mongorestore option was removed in v3.0, but not from the docs (oops). We should also clarify what the default writeConcern is for mongorestore.

This would be a good time to audit mongorestore for other potential sads.

From the source:

write concern options e.g. --writeConcern majority, --writeConcern '{w: 3, wtimeout: 500, fsync: true, j: true}' (defaults to 'majority')