encrypt whole ext hdd (ntfs, full) with...?

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http://forums.fedoraforum.org – as the title says, I want to encrypt some 2tb external hdds. truecrypt (realcrypt) does not support encryption of non-system volumes, I want to encrypt full hdds without creating a container. is there any other software supporting "in-place" encryption without data loss (obv)? btw, I'm currently running F17, how do I encrypt the home partition/system (missed the checkbox during install)? TIA (HowTos)