Time Machine drive encryption going for 22 hours. Is it stalled? I set up Time Machine in Mountain Lion by plugging in a newly formatted 500GB USB drive, selecting that from the Time Machine dialog, and checking the box to encrypt my backups. A window appeared that said "Preparing disk [diskname] for encryption." The progress bar quickly filled to about 80% and then stalled there. It's been about 22 hours now with no sign of progress. I know encrypting a drive can take a while, but is this too long? Should I force quit or unplug the drive and start over?

Notes:


I checked the system log to verify that the computer's been up and working all night; it didn't go to sleep. 
The drive is no longer showing up in the finder or Disk Utility. Is that normal when encryption is in progress?
22 hours is very long indeed. I have encrypted a 1TB drive in less time before.

The encryption is handled by a &quot;live background process&quot;. &quot;This
process continues seamlessly across reboots. The logical volume
remains usable at all times.&quot;
from man page &gt; diskutil &gt; encryptVolume

Maybe this daemon hangs or simply halted because the drive is not mounted (which is fine). So you should just re-mount it again.
Alternatively, I would try I restart the daemon by simply restarting the computer. Once the Time Machine backup is mounted again, the daemon will continue encrypting the drive.
Checking the encryption progress using diskutil
You can check the status of the encryption by using the command:
diskutil cs list

In the nested tree you will see a Logical Volume Family which is currently being encrypted. If you drive is being encrypted, you should see the entry Conversion Status:       Converting .
Encryption Status:           Unlocked
    Encryption Type:         AES-XTS
    Conversion Status:       Converting      //what does it say here?
    Conversion Direction:    forward
    Has Encrypted Extents:   Yes
    Fully Secure:            No
    Passphrase Required:     Yes