EC2 Instance became unresponsive and SSH failed until restart

Question

Our EC2 instance (US-West-2) became unresponsive, web traffic failed to connect, and I could not SSH into the server.

After shutting down and then launching the instance again activity and access have returned to normal, but I would like to know the cause so this doesn't happen again in the future.

I have checked the syslog files but there was nothing obvious logged that would have caused the issue

Any advice would be much appreciated

The instance_id: i-0d2dc06a6d078f519

The instance type is: c5a.2xlarge

Answer

If this problem reoccurs you might also try accessing the instance using the EC2 Serial Console. Another place to check is CloudWatch Metrics to see what the CPU usage is - there could have been a runaway process.

Otherwise, in cases like this I always recommend creating a support case and talking to the team about what the root causes may have been.

EC2 Instance became unresponsive and SSH failed until restart

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