Encrypting an existing Time Machine backup?

[mklnz]

I'm trying to encrypt an existing unencrypted TM backup, is this possible?
I read on a few sites that you can reselect the backup disk and tick the encrypt backup option, but when I do I get the following - it looks like I have to start fresh?

 

[prisstratton]

I'm trying to encrypt an existing unencrypted TM backup, is this possible?
I read on a few sites that you can reselect the backup disk and tick the encrypt backup option, but when I do I get the following - it looks like I have to start fresh?

This site says that this is possible, although there are caveats (GUUID partition table):

http://pondini.org/TM/31.html

Also, here:

http://osxdaily.com/2012/09/26/encrypt-time-machine-backups-mac-os-x/

The following thread is interesting, the OP is not describing the exact same set of circumstances as you, but there are some replies that suggest that the TimeMachine drive has to be identified as being "CoreStorage" for it to be encrypted. The OP has not responded whether this worked or not. Maybe keep an eye on this thread as it looks like it is still developing.

https://discussions.apple.com/message/20329196#20329196

Hope it helps………..

 

[mklnz]

Unfortunately I couldn't get it working, so I had to start fresh. I'll keep my old backup set on a separate encrypted drive for awhile and delete it after a few months.