AWS EC2 Rescue Mode: A DevOps Scenario for Freshers

DevOps Scenario-Based Series – For Freshers <5/100> AWS Rescue Mode Scenario: You are managing an EC2 instance hosting a production app. Suddenly, the instance becomes unreachable via SSH. On investigation, you realize: Disk utilization is 100% full Load average is extremely high You cannot even SSH into the instance Question: How will you recover this EC2 instance and bring it back to a stable state? Solution (Step-by-Step): Stop the Instance Go to the AWS Console → EC2 → Select the instance → Stop it. Detach the Root Volume From the instance details, detach the root EBS volume. Attach to a Helper Instance Launch/identify another healthy EC2 instance. Attach the detached volume as a secondary disk to this helper instance. Mount the Volume SSH into the helper instance. Mount the secondary volume (e.g., /dev/xvdf → /mnt/rescue). Free Up Space Navigate inside /mnt/rescue and check large files. Delete old logs, temp files, or move unused data to S3. Example: sudo du -sh * | sort -h sudo rm -rf /mnt/rescue/var/log/old_logs/* Detach and Reattach Unmount the volume. Detach it from the helper instance. Reattach it as the root volume to the original instance. Start the Instance Boot up the original EC2 instance. Now SSH should work fine. Prevention Tips: Use CloudWatch alarms to monitor disk usage. Implement log rotation to prevent oversized log files. Use EBS Auto-Scaling (gp3, io2) or EFS/S3 for heavy storage workloads. Learning: Rescue Mode (via detach/attach volumes) is a life-saving technique for AWS EC2 when normal SSH access is blocked. #justvisualise #AWS #EC2 #RescueMode #DevOps #ScenarioBased #100DaysOfDevOps