Aws Sla

Following my recent fascination about the cloud computing and Amazon Web Services (AWS) I looked deeper at the SLA that Amazon is offering for their Elastic Cloud Computing (EC2). And… it does not look as nice as it could.

  • The SLA states that Amazon guarantees 99.95% availability during the whole year, with minimal granularity of 5 minutes.
  • The problem is they redefine the term "Unavailable", which makes your availability less than 100%:
    • The whole Zone (aka Datacenter) must be unreachable, not just your instances (servers)
    • You are not able to launch new replacement instances in your Zone if your old instances die.

So what they CAN do is they can reset all your instances or even terminate them, but since "you are able to launch replacement instances" it is perfectly fine.