see this:
https://www.elastic.co/guide/en/elasticsearch/reference/5.6/modules-snapshots.html#_shared_file_system_repository

    Assuming that the shared filesystem is mounted to /mount/backups/my_backup, the following setting should be added to elasticsearch.yml file:

    path.repo: ["/mount/backups", "/mount/longterm_backups"]
    The path.repo setting supports Microsoft Windows UNC paths as long as at least server name and share are specified as a prefix and back slashes are properly escaped:

    path.repo: ["\\\\MY_SERVER\\Snapshots"]

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