– Vidur Apparao, CTO with LiveOps (www.liveops.com), says:
Understand how your cloud provider calculates availability
Many cloud technology providers provide Service Level Agreements (SLAs) around availability. However, make sure you understand how your provider actually calculates availability – five nines may not always mean what you think it does. The key is to clearly understand how your provider defines “downtime.”
- Some providers take “planned downtime” for maintenance or upgrades on a regular basis and don’t count this period in their availability calculation. If you are running a 24/7 operation, any downtime – planned or otherwise – will impact your service. A cloud provider should be able to maintain availability through maintenance and upgrade operations.
- A provider may not consider their service down for SLA calculation purposes unless it is completely down. There are times when a cloud platform could experience isolated delivery problems, but this may not be counted against your cloud provider’s availability. A provider’s SLA should reflect how well the provider is serving you and your users.
- Finally, a cloud technology provider may use network, infrastructure or platform services from its own vendors and partners. Some cloud providers do not take responsibility for the availability of these third-party services, even if they are critical elements of the primary service. A provider’s SLA should cover the availability of all of the services on which it depends.