Snapshot to the mounted NFS, without path.repo parameter in elasticsearch.yml

I have Elastic Cluster (version 5.6.0) with 9 data nodes and 3 master-eligible client nodes.
I want to backup date to the shared storage (NFS). So I am going to mount NFS to each node to the folder /mnt/backup and do something like this:

curl -XPUT 'http://localhost:9200/_snapshot/my_backup' -H 'Content-Type: application/json' -d '{
    "type": "fs",
    "settings": {
        "location": " /mnt/backup",
        "compress": false
    }
}'
  1. Can I do it without adding the path.repo parameter to elasticsearch.yml of every node? I have a lot of date, so adding this parameter to every node will take a lot of time.
  2. If I add this parameter, will I be able to continue making backups to s3?

Thanks

No, there is no alternative. The security manager needs to allow access to this path at startup.

Yes.