Root cause for AWS EC2 disconnection.



One of our production EC2 instances (Ubuntu 18.04 OS) became unreachable and we were unable to connect it via SSH. We rebooted the instance and then we were able to connect after that. Can someone point me to where should we check for the root cause for this problem? I could not find any useful info from the Instance's system logs as well.

asked 3 months ago33 views
2 Answers

Actually, it was almost at 0% utilization. This is the first time we faced this issue. Instance type is c5.2xlarge. We have also checked the disk usage. It was at 55%. Is there a possibility of some internal OS error on Ubuntu, that might have crashed it and made it unreachable? If yes, where could I find the logs?

answered 3 months ago
  • Server logs are saved in /var/log directory. You might want to check kern.log or syslog to rule out OS crash.


You should have a look at the Metrics for the instance. Especially the CPU Utilization, Status check failed metrics. See if there was high CPU utilization around the time you had to reboot instance. Depending on the instance type also look for CPU credit usage and balance.

Is it a recurring issue or one-off incident? What is the instance type?

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answered 3 months ago

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