Time machine - how to stop external hard drive encryption?

Question

Hi all
I've just gotten a larger hard drive and more RAM for my 1.5 year old MacBook Pro, running OSX 10.7.5. I restored my system using the latest Time Machine backup at the time from the external HD I want to continue to use. Somewhere along the line, after the restore, I must have replied "yes" to encrypt the external HD and now it's dong the encryption thing for hours and hours and hours. Looking at the contents of the external HD, it appears to have done backups whenever I've attached the external drive, so I think my data is secure.
The external drive is a Western Digital 2 TB, with a power cord. I'm using it for Time Machine and my Aperture vault. I may want to add my Bootcamp partition to the Time Machine, though I've been backing that up separately.
Is there any way I can suspend this encryption and set it to "no encryption" now that I've done the deed? I've looked through the community discussions on this (as well as Time Machine Help, and on the internet), and I don't see anything that guides me in this (at least, only something from earlier this year that indicates that I would have to reformat the external drive - is this still the case?).
Can I just shut down my MBP with this process going on? This HD is not USB powered, so I can't just carry the two machines to another location, as the external is plugged in and unplugging it would shut it off.
Would upgrading to Mountain Lion help with this situation? I'm thinking I want to do this anyway, as I like the sound of some of the new features.
Thanks so much.

Answer 1

The problem here is the way Apple chooses to implement Time Machine Backup in 10.6.x to a Network volume. When TM first came out myself and a bunch of similarly naive Unix hackers figured we could get the best of both worlds by backing up with Time Machine to a backed up or otherwise redundant network volume using Time Machine. But in the beginning TM didn't backup to network volumes. It does now by creating a sparse bundle on the network volume and backing up to the Sparse bundle as if it were a physical, local, disk drive. I seems logical to infer that Time Machine was written to backup to locally connected disk drives which differ from network disk drives in one very important respect: You can tell a local, physical disk drive that you need to know the status of any given write operation and you can trust that result with a reasonably high degree of confidence. That same can't be said for a write to network drive so Apple fakes it by creating a Pseudo Drive or Disk Image Drive on the network volume and writing way. The Sparse Bundle Error comes up when the Pseudo Drive wasn't put away correctly. There are filesystem repair programs to fix this condition which are described in other threads. Dig around for "fsck sparse bundle" on Google the next time this happens and you may be able to rescue things.