A: We don’t know the details of your support contract. You should check with your Oracle representative. We have heard anecdotal stories from MySQL Support team members that they have customers who use Percona Server with XtraDB, but you should not base your decision on that.
A: This is a common misconception about the GPL. We suggest reading the Free Software Foundation ‘s excellent reference material on the GPL Version 2, which is the license that applies to MySQL and therefore to Percona Server with XtraDB. That document contains links to many other documents which should answer your questions. Percona is unable to give legal advice about the GPL.
A: No, you don’t need to change anything on the clients. Percona Server is 100% compatible with all existing client libraries and connectors.
A: In case you’re using init script on Debian based system to start mysqld, be sure that the password for debian-sys-maint user has been updated and it’s the same as that user’s password from the server that the backup has been taken from. Password can be seen and updated in /etc/mysql/debian.cnf. For more information on how to set up a replication slave using Percona XtraBackup see this how-to.