AWS schedules events for your instances randomly due to hardware upgrade etc. Here are some of the scheduled events;
- System Maintenance
- stop/start, or
Here is the command to view details of a scheduled event for an instance.
aws ec2 describe-instance-status--instance-id i-xxxxxxxxxxxxx
where i-xxxxxxxxxxxxx is the instance instance (server) id
These events do not occur frequently. If one of your instances will be affected by a scheduled event, AWS will send out an email to the email address associated with your AWS account before carrying out this maintenance.
Note: Often times, depending on the event, you might be able to take action to control the timing of the event such as Stopping and starting the Instance again, thereby launching in on a new hardware.