Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have an external (non-system) drive with whole disk Truecrypt encryption.

When I mount the NTFS volume there is no option to compress contents in the drive->properties. And truecrypt mounted volumes don't show up in computer management->local storage.

Individual files and folders have the 'compress contents' box but it is disabled.

Is there any reason why you can't compress inside a truecrypt volume?

(Windows7, truecrypt 7.1, running as Admin)

share|improve this question
Encrypted data doesn't compress well, if at all, anyway. This is due to well-encrypted data being indistinguishable from random data while compression works by finding patterns in the data; the two are mutually exclusive if done properly. – Andrew Lambert Feb 6 '12 at 18:38
The compression is INSIDE the encrypted container. It will compress identically to any other data, the compressed (ie. essentially random) data is then encrypted – Martin Beckett Feb 6 '12 at 18:54
@Amazed: Compression should happen before anything is written to the disk, so this doesn't have an impact on encryption when writing at all. – Baarn Feb 6 '12 at 18:56

Fixed: NTFS encryption only works if you select default cluster size (4Kb)

I am using the device to store a few very large data dumps so had selected 64K

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.