adminMySQL Emergency Read Only Mode Checklist
In some incidents, you may need to stop writes temporarily to protect data. Read-only mode can help during migration, investigation, replication issues or suspected application behavior causing damage.
Core principle
Read-only mode is a containment tool. It reduces new changes while you investigate, but it can break application features that require writes.
Checklist
- Confirm why writes must be stopped.
- Identify affected applications.
- Notify or prepare for write failures if needed.
- Create a fresh backup before changing mode if possible.
- Enable read-only mode carefully.
- Verify read-only state.
- Test application behavior.
- Perform investigation or migration task.
- Disable read-only mode when safe.
- Document incident and data protection result.
Reusable lesson
This applies to database migration, incident containment, runaway writes, replication troubleshooting and emergency maintenance.
When to Use This Checklist
Use this checklist when you need to temporarily stop database writes during incident response, migration or emergency maintenance.
Required Tools
MySQL admin access, application owner, backup, maintenance plan, monitoring, rollback plan
Before You Start
Do not enable read-only mode on production without understanding which features require database writes.
Structured Checklist Steps
- Confirm need.
- Identify apps.
- Prepare for write impact.
- Create backup.
- Enable read-only.
- Verify mode.
- Test app behavior.
- Investigate issue.
- Disable read-only.
- Document result.
Verification Steps
- Write containment goal is clear.
- Read-only mode is verified.
- Application impact is understood.
- Mode is disabled when safe.
- Incident notes are complete.
Rollback Plan
If read-only mode breaks critical operations, disable it and use a narrower containment method such as maintenance mode or application-level write pause.
Common Mistakes
- Using read-only without app impact review.
- Forgetting to disable read-only.
- No backup before incident action.
- Assuming read-only protects every privileged user.
- No documentation of why writes were stopped.
Related Commands
mysql -u root -p -e "SHOW VARIABLES LIKE 'read_only';"
mysql -u root -p -e "SET GLOBAL read_only = ON;"
mysql -u root -p -e "SHOW VARIABLES LIKE 'read_only';"
mysql -u root -p -e "SET GLOBAL read_only = OFF;"
mysqladmin -u root -p status