Last Updated on August 7, 2025 by Arnav Sharma
Microsoft Azure offers a range of services including virtual machines, app services, and databases. Each of these services comes with a Service Level Agreement (SLA) – a guarantee from Microsoft regarding the availability and uptime of its services. Understanding the Azure SLA is crucial for customers to know what to expect in terms of service reliability and what compensations are available in case of any service disruptions.
SLA vs Allowable Downtime:
| SLA Uptime (%) | Annual Downtime Allowance | Monthly Downtime Allowance | Weekly Downtime Allowance | Daily Downtime Allowance |
|---|---|---|---|---|
| 99.00% | 87.6 hours | 7.2 hours | 1.68 hours | 14.4 minutes |
| 99.50% | 43.8 hours | 3.6 hours | 50.4 minutes | 7.2 minutes |
| 99.80% | 17.52 hours | 1.44 hours | 20.16 minutes | 2.88 minutes |
| 99.90% | 8.76 hours | 43.2 minutes | 10.1 minutes | 1.44 minutes |
| 99.95% | 4.38 hours | 21.6 minutes | 5.04 minutes | 0.72 minutes |
| 99.99% | 52.56 minutes | 4.32 minutes | 1.01 minutes | 8.64 seconds |
| 99.999% | 5.26 minutes | 25.9 seconds | 6.05 seconds | 0.86 seconds |
| 99.9999% | 31.5 seconds | 2.59 seconds | 0.605 seconds | 0.086 seconds |
Virtual Machine and SLA
When it comes to Azure Virtual Machines, the SLA varies based on the configuration. For a single instance virtual machine using premium storage, the SLA is 99.9%. This means that Microsoft guarantees you will have virtual machine connectivity to at least one instance at least 99.9% of the time. For virtual machines that have two or more instances deployed in the same Azure availability set or two or more availability zones, the SLA goes up to 99.95%.
Database Services and SLA
Azure offers various database services like SQL Database and Cosmos DB. The SLA for a single database instance in Azure SQL Database is 99.99%, ensuring high availability and consistency. Cosmos DB, known for its global distribution and throughput, also promises a high SLA, reflecting Microsoftโs commitments for uptime and connectivity.
Storage and SLA
Azure Storage guarantees an SLA of at least 99.9%. This includes Blob Storage, File Storage, and more, ensuring that data is available and redundant. The SLA describes Microsoftโs guarantee for uptime and the ability to retrieve data as needed.
App Service and SLA
Azure App Service, a platform for hosting web applications, APIs, and mobile app back ends, offers an SLA of 99.95%. This SLA ensures that your app is available and can intercept and handle requests as expected.
SLA Calculation: How It’s Done
Calculating the SLA of a system involves understanding the availability of each component. For instance, if you have an app service (99.95% SLA) connected to a SQL database (99.99% SLA), the overall SLA is calculated by multiplying these percentages: 99.95% * 99.99% = approximately 99.94%. This calculation is crucial to understand the overall reliability of your cloud services setup.
Premium Services and Free Tier Differences
Azure offers both premium and free services, each with different SLA levels. Premium services typically have higher SLAs, like 99.95% or 99.99%, while free services might have lower or no SLA guarantees, such as 99.5% or no SLA at all.
Service Credits: Compensation for SLA Failures
If Azure fails to meet its SLA commitments, customers are eligible for service credits. These credits are a form of financial compensation and are part of Microsoftโs guarantee to maintain a high level of service availability.
In summary, Azure SLAs are a key aspect of Microsoftโs cloud services, offering guarantees on service availability and uptime. From compute to storage, each Azure service has a defined SLA, which is essential for customers to understand. Knowing how to calculate the SLA for a combination of services, the difference between premium and free tiers, and the compensation available in case of SLA breaches are all critical for leveraging Azure services effectively. Azureโs SLA is not just a number โ it’s a commitment from Microsoft to provide reliable, consistent, and high-quality cloud services.