As Pioneer Rekordbox is being used more and more, I cannot tell people enough how to make a backup of your precious work. In Rekordbox it's rather easy to create a backup of your database with a few simple steps.
I would recommend everybody to make such a backup and store it after you did some work in Rekordbox (creating playlists, adding Cue/Loop points etc). This is the only way to get your hard work safe if something bad would happen to you computer or hard drive.
A hard-disk will alwyas crash at some point in time, the bad thing is that you never know when EOL of it has come.
Be aware that the backup will take a decent amount of time (depanding on your computer and size of music collection), even without the music files.
My backup if around 6000 tracks (they all have album art, a lot of them have cue info) is around 700MB wihtout the music files (that would add another 60GB )