Composite SLA

When combining SLAs across different service offerings, the resultant SLA is a called a Composite SLA.
The resulting composite SLA can provide higher or lower uptime values, depending on your application architecture.
Consider an App Service web app that writes to Azure SQL Database. At the time of this writing, these Azure services have the following SLAs:
- App Service Web Apps is 99.95 percent.
- SQL Database is 99.99 percent.
Composite SLA - 99.95 percent × 99.99 percent = ~99.94 percent
This means the combined value is lower than the individual SLA values, meaning higher probability of failure. This isn't surprising, because an application that relies on multiple services has more potential failure points.
Conversely, you can improve the composite SLA by creating independent fallback paths. For example, if SQL Database is unavailable, you can put transactions into a Queue for processing at a later time.

Last updated 4 years ago

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When combining SLAs across different service offerings, the resultant SLA is a called a Composite SLA.
The resulting composite SLA can provide higher or lower uptime values, depending on your application architecture.
Consider an App Service web app that writes to Azure SQL Database. At the time of this writing, these Azure services have the following SLAs:
- App Service Web Apps is 99.95 percent.
- SQL Database is 99.99 percent.
Composite SLA - 99.95 percent × 99.99 percent = ~99.94 percent
This means the combined value is lower than the individual SLA values, meaning higher probability of failure. This isn't surprising, because an application that relies on multiple services has more potential failure points.
Conversely, you can improve the composite SLA by creating independent fallback paths. For example, if SQL Database is unavailable, you can put transactions into a Queue for processing at a later time.

Last updated 4 years ago

Was this helpful?