I'm new to Truecrypt so I didn't quite get the hang of it yet. So, I started experimenting by creating a "standard", not "dynamic" 5MB file container and another one 10MB both are NTFS filesystem, AES encryption algorithm, and RIPEMD-160 hash.

However, when I checked the properties in the empty mounted volumes, I found that the 5MB had 2.97MB of used space, and the 10MB had 3.72MB of used space. Even though both were completely empty.

I tried using windows formating (quick) on both, nothing changed.

I know that NTFS file system uses some space for mapping, but 2.97MB out of 5MB seems like ALOT compared to normal NTFS and inefficient. If larger containers are created and a similar ratio of used space is maintained, I'd be losing alot of space.

What is the cause of this, and is there a way to avoid it?

  • @CodesInChaos I would check the file system. I meant NTFS in my post. Your readings are probably FAT.
    – Ray
    Mar 11, 2014 at 11:35
  • For a 10 GB the used space drops to 78 MB. How much used space does a 10 MB NTFS volume created by windows have? I never created such a small volume, so I don't know if your assertion that it is "ALOT compared to normal NTFS" is true. Mar 11, 2014 at 12:08
  • @CodesInChaos 78 MB vs 10 GB is better. But still, I have a 1 TB hard drive (single partition). The used space is some 130 MB.
    – Ray
    Mar 11, 2014 at 12:19
  • Could you present some evidence that the overhead for a volume created by TrueCrypt is larger than for windows created volume of the same size? To me it simply looks like the absolute overhead growing much slower than the volume size. Mar 11, 2014 at 12:21
  • @CodesInChaos You are correct. I have tried a 42 GB partition, and a file container within it, to cover the entire free space. Both had close to 91 MB of used space with very slight differences. So what you are saying is that the used space doesn't grow with the same rate as the volume itself?
    – Ray
    Mar 11, 2014 at 23:44


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