I am using a time capsule to backup my Mac. Since ML you have the option to encrypt your backups, which I did not do at the beginning. If you choose now to encrypt your backups, time machine will tell you that it will have to erase your existing unencrypted backups and start over. I don't mind starting from scratch but was wondering if time machine will erase the whole hard drive or the backups only? I am using my Time capsule as a NAS drive as well and have all my ripped movies on there. I assume that it will only delete the old backups but wanted to make sure someone can confirm. thanks.