Limitations

To backup multiple MySQL instances with the binary method and the xtrabackup tool, you must define multiple FileSet and multiple Job resources.
The xtrabackup tool doesn’t know how to read .my.cnf file to get user and password information. Thus you must specify the password in the plugin command line or to use the extra_file option in addition to the mycnf_dir parameter.
The Percona prepare option may only be used with Full backups. If you attempt to use the prepare option with an Incremental or Differental Percona backup, the backup will continue without the prepare option.
The Percona prepare option is incompatible with Bacula Encryption, Compression, and ACL options. If you use any of those options with the prepare option, the resulting backup will probably be unrestorable.

Note

All Percona backups use the xbstream program to backup the data. The xbstream program automatically uses compression.
The Percona prepare option only works with backups of a single MySQL instance. There may be multiple databases within that instance that are backed up.
With Percona prepare=fd the sized of the all-databases.xbstream as shown in the Bacula Catalog will alwas be reported as -1. This is because the stream is created on the fly with no intermediary file.
Most of the MD5 signatures for a Percona prepare will not be valid either because the file never existed on disk, or because the file was modified without recomputing the requested checksum.
In the current Percona prepare=sd implementation the Storage daemon’s Working Directory is used for placement of the temporary files. Consequently, it should be on a very fast device (RAID or SSD) and must be sufficiently large to handle the maximum database size for as many clients that can run simultaneously.
The backup of the Percona prepare=fd may include a few left over files of the Prepare process that are not really needed for a proper backup.
The Percona tools are tailor made for each operating system and for each version of MySQL. Therefore you must be very careful about upgrading either MySQL and/or the Percona tools. Please test carefully before trying to put them into production. Apparently with Ubuntu 16.04 the Percona tools that are part of their distribution were not upgraded when they added a newer version of MySQL. Consequently just doing an upgrade of that system can lead to Backup failures. In general, the Percona site has the most current versions you need for each MySQL version and also has a matrix of which versions work together.
The testing of the Percona prepare features was done with mysql Ver 14.14 Distrib 5.7.22 and Percona version 2.4.11.
As noted above doing a restore of a MySQL database on a system that uses AppArmor (Debian based, e.g. Debian, Ubuntu, …) can run into AppArmor permissions problems. Thus we strongly recommend that you try doing a Full restore of your MySQL installation in a test environment prior to putting it into production.
If you have MySQL binary mode backups and you plan to upgrade your MySQL server operating system, please confirm that Percona xtrabackup tools are available for the platform you plan to upgrade the system. MySQL binary mode backups use the Percona xtrabackup tools and they must be available for the new operating system version/platform of your MySQL server.
The restart command has limitations with plugins, as it initiates the Job from scratch rather than continuing it. Bacula determines whether a Job is restarted or continued, but using the restart command will result in a new Job.