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1. Regional Failover Patterns2. Chaos Testing for AI Services

Regional Failover Patterns

📚 Multi-Region Resilience10 min115 XP

Failover Is a Product Requirement

Use active-passive or active-active strategies depending on your latency and compliance profile. Bedrock adds one twist classic DR plans miss: the same model may not exist - or behave identically - in your failover region, so model equivalence is part of your failover design.

Strategy Options

StrategyShapeCost/complexityFit
Cross-region inference profilesAWS routes across a geography automatically (us./eu. prefixed IDs)Lowest - built inFirst line of defence for throughput + regional blips
Active-passiveStandby region with config + quotas pre-provisioned; DNS/flag flip to fail overMediumMost teams; clear runbook, bounded spend
Active-activeBoth regions serve traffic continuouslyHighest - double quotas, sync complexityHard availability targets, global user base

The Model Equivalence Map

# failover-map.yaml
primary:   us-east-1
secondary: us-west-2
models:
  amazon.nova-pro-v1:0:      same-id          # verified available
  anthropic.claude-sonnet-*: us.profile       # cross-region profile covers both
  custom.triage-ft-v2:       nova-pro + prompt-v3-fallback   # custom models don't failover - plan the substitute!

Custom models and Provisioned Throughput are region-bound - your failover plan must name the substitute and accept its eval-scored quality delta in advance.

What Must Be True Before You Can Fail Over

  • Model access granted in the secondary region (it is account+region scoped - module 2).
  • Quotas raised in the secondary - default TPM in an unused region will not absorb your production load.
  • Guardrails, prompts, KB replicas deployed - inference without your safety config is not a failover, it's an incident.
  • Data residency audited - an EU workload failing over to us-east-1 may trade an outage for a compliance breach.
  • Runbooks tested and current - untested failover plans fail at the worst possible moment (next lesson: chaos drills).
Quota trap: teams provision failover infra but forget service quotas. The failover "works" - at 5% of required throughput. Request secondary-region quota increases as part of DR setup, not during the incident.
🧪 Knowledge Check
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Why maintain region model equivalence maps?
For aesthetics
To ensure predictable behavior during failover
To remove IAM
To avoid backups