Formal agreement between service provider and customer
SLA is the promise of the availability of an service (uptime and connectivity)
SLA is a per month Availability agreement
Each service has a different SLA
Free services generally do not have an SLA
If SLA is broken user gets credit token (Discount)
Monthly Uptime Percentage = (Max Available Min - Downtime) / Max Available Min * 100
Composite SLA
Combined SLA of services that are used in our application
Logical AND
Both services are required for functioning of application
SLA = Sa * Sb
Logical OR
Both services are not required for the functioning of application
SLA = 100% - (Sa * Sb)
Factors that lower SLA
Adding more services
Using free/ preview services
Factors that increase SLA
Adding redundancy
Changing service configuration