# Making AI Calls Highly Available: Multi-Node Failover & Cross-Provider DR

> AI gateway HA: multi-node failover, cross-provider fallback (OpenAI 503 auto-switch), shared state across instances, canary rollout. Self-hosted, no SaaS single point.

Canonical: https://www.gatellm.io/use-cases/high-availability/

Load balancer for multi-node failover, provider-level disaster recovery, shared state across instances, canary rollout — no longer held hostage by a single provider's outage.

## What the community actually complains about
A common refrain on Reddit: "OpenAI has one 503 and the whole product goes down." Direct-to-one-provider is a single point of failure; add cross-ocean timeouts, 429 rate-limit queuing, and instance OOM mid-stream.
You need millisecond failover with no code changes.

## How GateLLM does it
GateLLM supports cross-provider fallback: when the primary returns 5xx / times out, traffic moves to a backup provider with no business-code change. The load balancer does multi-node failover and canary rollout with shared state across instances.
Self-hosted in your VPC, no SaaS gateway as a single point itself.

## 5 levers that actually land
- Load balancer: multi-node failover and weighted routing
- Cross-provider fallback: primary 5xx / timeout auto-switches to a backup provider
- Provider-level DR
- Canary rollout: new versions ramp by traffic, auto-rollback on errors
- Shared state across instances, so failover and canary rollouts stay consistent

## FAQ
### How does an AI gateway handle provider outages (e.g. OpenAI 503)?
Cross-provider fallback: when the primary returns 5xx or times out, traffic moves to a backup provider with no code change; the load balancer does multi-node failover, and self-hosting removes the SaaS single point.

### How do multiple instances do canary rollout?
Instances share state; new versions ramp by traffic and auto-rollback on errors, avoiding all-at-once rollout traps.

- [Full how-to: High availability (docs)](https://docs.gatellm.io/en/usecases/high-availability)

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