Technical Tip: Upgrading FortiProxy cluster devices with uninterruptible upgrade and sequential upgrade options

By default, FortiProxy cluster has uninterruptible upgrade and sequential upgrade settings enabled. 

Default Behavior:

By default, FortiProxy clusters have the following HA settings enabled:

1. uninterruptible-upgrade: Enabled (minimizes downtime by upgrading subordinates first).
2. sequential-upgrade: Enabled (upgrades secondary nodes one at a time in larger clusters).

Upgrade behavior:

1. Both enabled (default): The upgrade is done on secondary devices one at a time. After all the secondary devices are upgraded, a new master is chosen among them, followed by the upgrade of the current master.

2. Sequential-upgrade disabled: The upgrade is done on all secondary devices at once, followed by the upgrade of the current master.

3. Uninterruptible-upgrade disabled: All the cluster members are upgraded simultaneously (faster but causes full service interruption).

Note: This also applies to FortiProxy cluster in config-sync only mode.