Scenario : High CPU
A server's CPU is at %. How do you investigate?
. Run top or htop to identify the process
. Check if expected or a bug
. Use strace -p [pid] to see what it's doing
. Review application logs
Scenario : Out of disk space
Disk shows full but du doesn't account for all space.
. Check for deleted files held open: lsof | grep deleted
. Restart the process holding files
Scenario : Process won't start
A service fails immediately after starting.
. Check systemctl status servicename
. Review journalctl -u servicename
. Verify permissions and dependencies