From The Open Source Backup Wiki (Amanda, MySQL Backup, BackupPC)
ZRM for MySQL uses plugin to tailor backups for specific needs. The following plugins are used to customize backup runs.
Pre Backup plugin is invoked before a backup run is started
Snapshot plugin is invoked during backup run when snapshots are used during backup
Post Backup plugin is invoked after a backup run is completed
Copy plugin is invoked if backup from a remote MySQL Server is required.