Set up high availability
Estimated reading time: 1 minuteDocker Universal Control Plane is designed for high availability (HA). You can join multiple manager nodes to the swarm, so that if one manager node fails, another can automatically take its place without impact to the swarm.
Having multiple manager nodes in your cluster allows you to:
- Handle manager node failures,
- Load-balance user requests across all manager nodes.
Size your deployment
To make the swarm tolerant to more failures, add additional replica nodes to your swarm.
| Manager nodes | Failures tolerated |
|---|---|
| 1 | 0 |
| 3 | 1 |
| 5 | 2 |
For production-grade deployments, follow these rules of thumb:
- When a manager node fails, the number of failures tolerated by your swarm decreases. Don’t leave that node offline for too long.
- You should distribute your manager nodes across different availability zones. This way your cluster can continue working even if an entire availability zone goes down.
- Adding many manager nodes to the cluster might lead to performance degradation, as changes to configurations need to be replicated across all manager nodes. The maximum advisable is seven manager nodes.