Percona XtraDB FAQ
Q: Why XtraDB ?
A: eXtra performance, eXtra scalability, eXtra features.
Q: What is the license? Is it free?
A: We distribute the storage engine under **GPLv2** license, and it is absolutely free to use. No dual-licensing. No community and enterprise separation.
Q: Do I need to convert all my tables to the XtraDB engine?
A: NO. The XtraDB plugin is designed to be used instead of InnoDB, and is fully compatible with your existing InnoDB tables and server settings. To create new tables you still use CREATE TABLE … ENGINE=InnoDB.
Q: How do I install XtraDB?
A: It depends. There are several ways:
install into running MySQL 5.1. In this case installation procedure is the same as installation of InnoDB plugin. We have shared library prepared for x86_64 platforms.
install MySQL-5.1.30-percona binaries with build-in XtraDB. We have x86_64 RPMS for RedHat / CentOS 4 and 5 systems.
install from sources. Non trivial way, you need percona-xtradb.tar.gz with source code and then follow installation from sources for InnoDB
Q: How do I uninstall XtraDB?
A: uninstall is the exactly the same as for InnoDB plugin
Q: How can I revert back to InnoDB?
A: Just uninstall XtraDB and use the InnoDB plugin instead. You don't need to convert any of your data files, modify any settings, or make any other changes. If you want to revert back to the version of InnoDB that is shipped with the official MySQL builds (e.g. not the InnoDB plugin) then you can use the InnoDB plugin's downgrade procedure.
Q: What is the risk? Can it corrupt my database?
A: Although we tested it as well as we can, there is always a risk. XtraDB modifies InnoDB kernel significantly, and it is possible there are some bugs. No one has reported any crashing or corruption issues so far.
Q: Where can I report bugs?
A: We accept bugs in Launchpad bug tracker
Q: Is commercial support available?
A: Yes, Percona provides commercial support for XtraDB. If you are interested, please contact us to discuss.
Q: How can I request a new feature?
A: You can request it on the Launchpad Blueprints, or discuss in public groups Percona Dev or Percona discussion
http://www.percona.com/docs/wiki/percona-xtradb:info:faq