I am setting up my 3 node cluster to create snapshots nightly. I know I have to make sure the snapshot location is available on all nodes and register the shared files system repo on each node but do I actually run the backup on each node or does one node discover and backup the primary shards off any node where they are located? Also, by default does it only backup primary shards or is there a way to configure this? I don't want the replica shards backed up. Thank you for any help.
does one node discover and backup the primary shards off any node where they are located
Yes, the master node coordinates the snapshot. It will instruct each node that has primary shard to write to the shared file system.
Only primary shards will be used for snapshots. This is not configurable.