Practice and reference
Read the concept, then use a quiz, builder or checklist to make it stick.
First response goal
The goal is to reduce uncertainty quickly. Confirm the symptom, gather evidence, avoid risky assumptions and create a clear next action.
Do not make destructive changes just to see what happens. That is not troubleshooting. That is jazz with root access.
Checklist
- Confirm the exact application error
- Check service status
- Check disk and memory pressure
- Review MySQL or MariaDB logs
- Check large databases and tables
- Look for recent code or plugin changes
Useful commands
$ systemctl status mariadb
$ mysqladmin processlist
$ mysql -e "SHOW DATABASES;"
$ du -sh /var/lib/mysql/* | sort -h | tail
What good notes include
- The exact symptom and timestamp.
- The command or tool used to verify it.
- Relevant output, trimmed and sanitised.
- What was ruled out.
- Recommended next action or escalation reason.
Customer-safe summary
Explain what was checked, what was found, and what the customer can do next. Avoid dumping raw logs unless they help. Clear beats clever.