A Service Level Agreement (SLA) is an agreement that describes the detailed characteristics of the service, the rights and obligations of the customer and supplier, as well as the level of availability of the target service.
Virtual infrastructure for rent
The SLA states, among other things:
- The agreed working time, SVR (for example, “24×7” implies round-the-clock operation, seven days a week)
- Agreed support time, SVP (for example, “8×5” implies “10:00 – 18:00, Mon-Fri”)
- Downtime
- Reaction time
The key point of the SLA is the actual availability, which sets the percentage of service availability for the billing period. It is calculated according to the formula: (SVR per period – downtime per period) / SVR) × 100%. For example, 99.95% availability means that the total downtime should not exceed 22 minutes per month. The indicator can be calculated both for the infrastructure or the network as a whole, and for individual services, depending on the type of service.
The SLA also prescribes the level of functionality of the disk subsystem (IOPS, latency), temporary “windows” of maintenance (planned, urgent), and compensation amounts.