Azure SLAs

1. What is an SLA?

A Service Level Agreement (SLA) in Azure defines the uptime and performance guarantees provided by Microsoft for a specific service. If the SLA is not met, customers may receive service credits as compensation.

2. Azure SLA Plans

🔹 Subscription-Based SLAs – Higher-tier plans offer better guarantees. 🔹 No SLA for Free Plans & Preview Services – These services are not covered by availability guarantees.

3. Service Credits

If an Azure service fails to meet its uptime commitment, customers can request service credits based on the downtime percentage.

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4. Azure Composite SLA

A Composite SLA is the combined reliability of multiple dependent services. It is calculated by multiplying the SLAs of individual services.

🔹 Adding More Services Lowers SLA – The overall reliability decreases as more dependent services are added. 🔹 Adding Redundancy Improves SLA – Deploying services across multiple zones/regions increases availability. 🔹 Zonal & Regional Redundancy – Services with built-in geo-replication have higher SLAs. 🔹 Different SKUs & Service Tiers – Premium tiers offer better uptime guarantees than basic ones.

Example: Composite SLA Calculation

VM SLA = 99.9%
Storage SLA = 99.99%
Then, the Composite SLA = 99.9% × 99.99% = 99.89% (lower than the individual SLAs).