If I encrypt a Time Machine backup disk, is the entire disk encrypted or just the Backups.backupdb directory? If I check the "Encrypt backup disk" checkbox in Time Machine (in OS X Lion), I get this warning:


Will just the Time Machine "Backups.backupdb" directory be encrypted, or the entire disk?  In other words, will computers running earlier versions of OS X than 10.7 be unable to access the entire disk, or just be unable to back-up to or restore from the encrypted disk?
It encrypts the partition that you use for Time Machine, which likely means the entire disk. If you partition the drive the other partitions will not be encrypted and should mount (I have not tested this).



You can see that "Time Machine" is encrypted, but "Other Backups" is not.