We have a total of 3 appliances. Primary, Secondary and DR.
1) What should be the upgrade path, all the way from 8.1 to 8.3 on primary and then others OR step by step upgrade of primary and replicas to intermediate upgrades?
2) If there will be any downtime at any point in the upgrade? When the primary is upgrading, can the other two appliances authenticate the users?
3) While upgrading the Primary, at what stage will it be important to promote the replica to the primary?