EC2 Fault Tolerance
ec2 aws fault-toleranceGoing through a course for my AWS Solutions Architect Associate cert. Learned about planning for fault-tolerance with EC2 instances.
Apparently the trick is to think of the worst case failure. For example, say you have three availability zones (AZs), and three MUST have 100% availability.
Think of the worst case failure, i.e. the AZ with the most number of EC2 instances fails. Then come up with a setup that has three instances running, despite the failure. That leads to setups like:
- 3 in
AZ-0
, 2 inAZ-1
, 1 inAZ-2
- 2 in
AZ-0
, 2 inAZ-1
, 2 inAZ-2
In either of these cases, even if the worst case scenario happens, you’re still abiding by your SLA.