Where is the official documentation for Amazon EC2 rebooting instances for hardware changes?

Tag: amazon-ec2 Author: zhu_cezhu_ce Date: 2011-05-15

I understand that the Amazon EC2 SLA says that EC2 guarantees a 99.95% uptime.

I've read in many places that systems built using EC2 should be designed to cope with individual instances being restarted e.g. ec2 rebooted my instance.

Where is the official Amazon documentation to say that instances may be restarted?

Other Answer1

I do not believe Amazon publishes any documentation on rebooting EC2 instances for hardware changes. Instead, they will send customers a notice if there is going to be scheduled maintenance performed on the system. However, I think the issue here is more a matter of servers crashing unexpectedly. That, of course, they cannot announce beforehand. Also, don't forget that they calculate their uptime based upon 5 minute increments so you may have downtime that isn't counted towards their SLA because it was less than the five minutes and didn't get noticed.

Here is a link to the official Amazon EC2 SLA (I'm sure you've seen it). They don't give any indication that maintenance ever affects systems running in production:

http://aws.amazon.com/ec2-sla/

You can contrast this with Amazon RDS, which specifically states what maintenance is and when it occurs:

http://aws.amazon.com/rds/faqs/#12

I would imagine that they expect to never have downtime because of hardware upgrades. Since everything is virtual, they can move live instances to new hardware without taking them down.