What should I ask at a MySQL DBA interview?
Not a complete list, but rough list of things I would try to cover. It also depends on whether they will be the first "true" DBA or in a DBA team. Whether the DBA is responsible for the machines, too, or only the database on top of that. etc.


what RAID configuration should be used
backup strategies for databases.
MySQL specific things like differences between MyISAM and InnoDB
backup strategies and recovery
Let them do some SQL queries and some query optimization (usage of explain etc. even when using hibernate. Sometimes it's good to bypass hibernate to gain performance)
did I mention backup strategies
For scalability a DBA should know about different replication modes (RBR, SBR, mixed mode replication, replication maintenance such as observing replication lag and binlog maintenance)
InnoDB tuning
What kind of files are being written by the DB (eg, ibdata and log files) and how they can be arranged (eg, one ibdata file per table, move them around on different partitions, InnoDB compression)
Discuss monitoring tools. What are you using, do they have experience with that tool or a similar one?
I'd also look into system tools like iostat/memstat/vmstat/whatever your OS provides.  Give them a system with some load and let them find the cause
And maybe discuss issues in MySQL backup and especially restore ;-)


I'm sure others here can extend this list