AWS vs Azure vs Google Cloud: Reliability Compared

Choosing a cloud provider often comes down to features and pricing, but reliability should be a key factor. Here's how AWS, Azure, and Google Cloud compare when it comes to keeping your services running.

Uptime Track Records

All three major cloud providers target high availability, but their track records differ:

AWS (Amazon Web Services)

AWS is the oldest and largest cloud provider, giving them the most operational experience.

Notable incidents:

• US-East-1 has historically been their most problematic region
• S3 outage in 2017 took down a significant portion of the internet
• Multiple Kinesis outages have caused cascading failures

Strengths:

• Most extensive global infrastructure (30+ regions)
• Mature tooling and documentation
• Best ecosystem of third-party integrations

Microsoft Azure

Azure has grown rapidly but has had notable reliability challenges.

Notable incidents:

• Multiple global authentication outages affecting Microsoft 365
• DNS and certificate issues causing cascading failures
• Azure Active Directory outages impacting enterprise customers

Strengths:

• Excellent for Microsoft-centric organizations
• Strong compliance certifications
• Good hybrid cloud capabilities

Google Cloud Platform (GCP)

GCP benefits from Google's experience running massive internal systems.

Notable incidents:

• Global outage in 2019 due to network configuration error
• Multiple Cloud Console outages
• Fewer overall incidents but tends toward global impact

Strengths:

• Superior network infrastructure
• Strong Kubernetes support (created Kubernetes)
• Best data analytics and ML capabilities

Reliability Features Compared

Regions and Availability Zones

• **AWS**: 30+ regions, 90+ availability zones
• **Azure**: 60+ regions, complex availability zone model
• **GCP**: 35+ regions, with emphasis on multi-region services

More regions don't always mean better reliability. What matters is how services fail over between zones and regions.

SLA Guarantees

All three offer similar SLAs on paper:

• Compute: 99.9% to 99.99%
• Storage: 99.9% to 99.999999999% (11 nines for durability)
• Databases: 99.95% to 99.99%

The differences are in the fine print. Read the SLA documents carefully, as what constitutes downtime varies.

Redundancy Options

AWS:

• Multi-AZ deployments
• Cross-region replication
• Global Accelerator for traffic management

Azure:

• Availability Sets and Zones
• Azure Traffic Manager
• Geo-redundant storage options

GCP:

• Regional and multi-regional resources
• Global load balancing by default
• Spanner for global database needs

How They Handle Incidents

Status Page Quality

All three have public status pages, but their transparency varies:

AWS: Generally detailed but sometimes slow to acknowledge issues. Status page can be affected by the outage itself.

Azure: Has improved transparency significantly. Now provides detailed incident communications.

GCP: Generally good transparency with detailed post-mortems published publicly.

Post-Mortems

Google publishes the most detailed public post-mortems. AWS rarely publishes detailed analyses. Azure has improved their post-incident communication recently.

Architectural Recommendations

Regardless of which provider you choose:

Design for Failure

• Assume any single component will fail
• Use multiple availability zones minimum
• Consider multi-region for critical workloads

Don't Trust Defaults

• Default configurations optimize for cost, not reliability
• Enable cross-zone load balancing
• Configure appropriate health checks
• Use connection draining

Monitor Third-Party Dependencies

• Even within a cloud provider, some services are more reliable than others
• Core compute is usually more reliable than newer services
• Monitor using external tools, not just the provider's monitoring

Consider Multi-Cloud

For critical systems, multi-cloud provides insurance against provider-wide failures:

• **Pros:** True redundancy, negotiating leverage, avoids lock-in
• **Cons:** Complexity, cost, operational overhead

Most organizations are better served by multi-region within one provider than multi-cloud.

The Verdict

There's no clear winner. Each provider has strengths:

• **Choose AWS** if you need the broadest service selection and most mature ecosystem
• **Choose Azure** if you're heavily invested in Microsoft technologies
• **Choose GCP** if network performance and data analytics are priorities

More important than which provider you choose is how you architect your applications. A well-designed application on any major cloud will be more reliable than a poorly designed one on the best cloud.

Monitor all your cloud services on Outage.com to get early warning of issues, regardless of which provider you use.