Cannot Connect to Database
| What to do |
|---|
| Check if mysqld is running and if the ports are available. Both on the localhost and from the host you try to connect from. See if the service is running and if you can connect locally. This should usually provide the information needed to troubleshoot from. |
| Actions |
| Log the start of the incident and indicators |
| Check monitoring |
| Check the logging less /var/log/mysql.log |
| Check mysqld service service mysqld status |
| Check load on database server using top |
| Check the ports using nmap -Pn localhost |
| Check the ports from remote using nmap -Pn databasehost |
| Try to login locally on the database server mysql -u root -p |
| Try to login from the remote host mysql -h databasehost -u dbusername -p |
| Fixing (you might kill the webserver/monitoring first) |
| Restart mysql service service mysqld restart |
| Follow the logging tail -f /var/log/mysql.log |
| Check mysql service service mysqld status |
| Last resort reboot perhaps check most recent backup first |
| Restore most recent backup, dump the database first |
| Post actions |
| Reactivate monitoring |
| Log actions and problem resolution |
| Keep an eye on monitoring and logfiles |
| Log rootcause, lessons learned and pending actions |