On all our plans we have MySQL selected. We’ve never even tried to change the default.
For some reason however, when selecting Features and Plugins, the Default was no longer selected.
Not entirely sure why this is so, changing it to Default bizarrely gives a BIND error:
Failed to save enabled features : Errors were found in your system's BIND configuration : /etc/bind/named.conf.local:12114: writeable file '/var/lib/bind/example.org.hosts': already in use: /etc/bind/named.conf.local:4909
So what happened this weekend, is not knowing that it’s “no longer selected” for whatever reason, we en-masse assigned packages from the Default Plan to a New Plan.
In the process every single database got deleted (around 120). We used the command line API to automate the package changes.
Thankfully we had daily backups and were able to recover two days ago’s backup.
So far my conclusion is that when you create a new plan, when BIND is checked and fails, and the new plan then decides to not use MySQL. I’m not sure what’s going on but I nearly saw my entire hosting business blow up.