The docs on snapshots (https://www.elastic.co/guide/en/elasticsearch/reference/current/modules-snapshots.html) say:
"The shared file system repository ("type": "fs") uses the shared file system to store snapshots. In order to register the shared file system repository it is necessary to mount the same shared filesystem to the same location on all master and data nodes. This location (or one of its parent directories) has to be registered in the path.repo setting on all master and data nodes."
But if the repository folder is already created on each node, what else is achieved by adding it to path.repo?