Can Acronis or Macrium Reflect backup Truecrypt?

pcwin · 06 Aug 2015

I have created a 100GB truecrypt file data.tc

I intend to use a backup software and set daily auto incremental backups. .

Lets say

On day 1 (Aug 1), I created a full backup data.tc and scheduled daily incremental backups everyday (from day 2 onwards the backup software will be creating incremental backups).

On day 4 (Aug 4), I added fileday4.txt into data.tc (I mounted data.tc and put fileday4.txt into data.tc)

On day 5 (Aug 5), I added fileday5.txt into data.tc (I mounted data.tc and put fileday5.txt into data.tc)

On day 6 (Aug 6), I edited fileday5.txt (in data.tc) and added some text

Will the incremental backup on day 7 (Aug 7) contain the fileday4.txt and fileday5.txt with accurate data?

Lets say I recover data.tc from my backup of day 7 (Aug 7), will I see fileday4.txt and fileday5.txt inside the data.tc when I mount data.tc?

My question is does Acronis or Macrium Reflect backup the changes I made in Truecrypt file container?

I am asking this because I always see the data.tc as 100GB size and it does not change in size, so I was wondering if the backup software could "see" the files inside data.tc when I add or make changes and make backup to it. Or does the backup software always see the data.tc as a 100GB size file and assume that the file has not changed, thus the backup software does not make new backups to data.tc even I have added files to it.

Thanks :)

ignatzatsonic · 06 Aug 2015

I'd imagine the best place to get an answer to that would be at the Macrium and Acronis forums hosted by those 2 companies.

You are layering two levels of complexity on top of basic imaging: incrementals and encryption. That may be doable and problem free, but I'd be very very I say very cautious and would need very good reasons to insist on both of those complications.

There's no substitute for your own testing. Try what you propose and see what happens. And then try to convince yourself that the results of your testing will persist into the future.

Alejandro85 · 08 Aug 2015

Programs other than Truecrypt itself know nothing about Truecrypt's containers and just treat them like some random blob of unintelligible data. That's the whole point of encryption, to make programs not understand some data.

Backup programs are no different from this. When directed to backup a container, they see a single, large file, but are completely unaware of what it is, much less its inner files. They can totally back it up like everything else (backup programs don't care about the content after all), but using incremental backup won't get the desired results if used on the container file.

When adding files to a Truecrypt container, the .tc file will obviously change (rather dramatically, if the encryption is good enough) but from the backup point of view, the single 100GB file changed. It will realize of the change based on the "archived" attribute or on the "last modified" date, not on the overall file size, that in particular for Truecrypt will remain constant. The result is that it will copy another 100GB as an "incremental" backup. It will effectively backup the changed container, but the net result is not exactly what one would call incremental.

Another approach could be to direct the backup program to the mounted container virtual drive instead of the container itself. This time it will be able to find all the inner files (like all other programs, because Truecrypt is under the hood encrypting/decrypting in real time) and incrementally backup each individually. Problem is that this will bypass the encryption for the backed up data, as it will yield a bunch of normal files, not a Truecrypt container.