Currently xrootd will happily start even if it can't connect to mysql, it will only print a message:

Configration invalid: Unable to connect to MySQL with config:

This can be easily overlooked, plus, it is a fatal error and xrootd initialization should be aborted.

while working on this, I propose to also improve validateMysql(). At the moment it connects to mysql and database in one call. If connection is fine, but the database does not exist, it will fail without telling user why it failed. This can be confusing. It'd better to connect to mysql without connecting to database, then do "select_db", and if that fails, inform the user that the database does not exist.

(transferred from trac ticket 3165)