Upgrading a Nomad Server cluster follows the core principle of “backup first, rolling upgrade, Followers before Leader”. Since Nomad relies on the Raft consensus protocol, Quorum must be maintained throughout the upgrade process, otherwise the cluster becomes unavailable.

Here is the detailed upgrade procedure:

Upgrading a Consul cluster must follow the principle of “step by step, Servers before Clients, maintain compatibility”. If the version gap is too large (e.g., jumping from 1.1x directly to 1.2x), a direct upgrade may cause Raft protocol incompatibility or data corruption.

Below is a detailed upgrade roadmap and procedure: