Backup libraryMB is equipped with a native backup feature that helps users to store in a safe place their settings files and music files in library for a data loss or unexpected system failures.
After clicking on the menu (File> Backup Library), the user needs to choose a source folder and its backup folder for each line before execution.

It would be a good idea to backup your music, audiobook, video files in addition to the default settings files. The entire MusicBee program folder too could be added to keep copies of album artworks, artist pictures, skins and theater mode views of your collection.
MB's backup is incremental backup, meaning it only updates modified files, plus deleting non-existent files and empty folders and adding new files, instead of completely rewriting everything. Once the first backup is done, therefore, it won't take much time to backup from the second time unless a great portion of the library have been modified. After each backup is done, the content of the backup folders should exactly reflect the current state of each source folder.
Notes:
1. MB library folders and files (playlists, podcasts, library database files, etc.) are not included in the default "MB Settings folder". If you want to backup those too, you have to include them manually.
2. Do not use this feature with existing folders for a test. All files in the target folder that are not present in the source folder will be deleted.