Instance reachability check failed

Question

Hello,
I have the Instance reachability check failed problem in which I'm stumped.

As a background, there is a bug in my server program which causes it to write huge log file (193GB). Due to this, I promptly stopped the EC2 Server, and started it again.
This is when the issue happened, it shows Instance reachability check failed.

Things I have tried : 
- I tried stop/start the instance multiple times.
- I have checked all the error keyword documented here, but no same case found in my system log.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/TroubleshootingInstances.html#system-log-errors-linux

My EC2 uses EBS with 250GB storage. Does EC2/EBS prone to have problem when stop/started when writing a log? To make things worse I dont have backup for the EBS.
Attached here is system the log I get from the Instance.
https://drive.google.com/file/d/1HfQ7Ipf8fHZuexNuJbxn5wm3r_ItuIAk/view?usp=sharing

Hopefully I get enlightenment here.
Thank you in advance.

Riku_Kobayashi · Accepted Answer

Hello.

How about mounting the root volume on another EC2 and retrieving the necessary data and restoring the application etc.?  
https://docs.aws.amazon.com/ebs/latest/userguide/ebs-using-volumes.html

When mounting an EBS volume, an error will occur if the UUID is duplicated, so try running the command with the "-o nouuid" option as described in the document below.  
https://repost.aws/knowledge-center/ebs-mount-volume-issues

BCAP · Answer

Hello, thanks for the answer!
I mounted the problematic EBS to another working server. I'm able to access the files, and proceed to delete the massive log file.

After deleting the log file, I try to run the EBS Server again and now it works. Seems like the massive log in my EBS causing the issue when booting up the server.

Instance reachability check failed

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