Comments on: Using A File As A Storage Device

By: prasadjadhav

prasadjadhav — Fri, 21 Sep 2012 07:18:20 +0000

Reblogged this on Welcome To Prasad Linux Blog.

By: animaletdesequia

animaletdesequia — Wed, 31 Aug 2011 18:55:49 +0000

Thanks for your answer. I opened a question here:

http://askubuntu.com/questions/58935/how-do-i-create-an-encrypted-file-system-inside-a-file

There’s an alternative method using cryptmount, and I manage to make it work, but anyway i’ll try this one since if I’m not wrong crypsetup is from the gnu project, I supose this metod is more like using build-in tools.

I’ll check your article when you publish it

By: flossstuff

flossstuff — Wed, 31 Aug 2011 18:25:51 +0000

“I mean in what situation would warrent the use of a file as a storage device for daily use?
Does it reduce disk fragmentation? Does it make consolidation of files for backup simpler?
For testing, I assume it makes sense to create file and dump different file systems for experimentation.”
As animaletdesequia pointed out in comment above, you can simply mount the encrypted file that is in the dropbox folder, as your home folder. So, that even on cloud your files are safe.
Also, Lets say you have four partitions, /dev/sda1, sda2, sda3, sda4. Now, sda1 is running out of space. But, sda4 has 10GB free space. So, since sda4 is at the end of the disk, and sda1 at the beginning, you will have to resize all of them just to get some extra spade in sda1. Instead, you could just create a file on sda4 and mount it inside a sub-folder, where sda1 is mounted.
About backup, yes it does make backup simpler, rather than having to archive, you can just copy one file. But there is also a disadvantage, if you create a 2GB file, and mount it. Only 1GB is used. But, while making backup you will have to copy the entire file. So, you will end up copying 1GB more. You could make a small file and extend it as you are using it. But, than can be a lot of work for some people.
About fragmentation, I guess it could reduce disk fragmentation.

By: flossstuff

flossstuff — Wed, 31 Aug 2011 18:12:31 +0000

Thank u for feedback animaletdesequia.
here is how to create an ext4 encrypted file
1. losetup /dev/loop0 /newfile where new file is the file we created earlier.
2. cryptsetup -c aes create newhome /dev/loop0
it will ask you for passphrase.
now create ext4 filesystem on the file
3. mkfs -t ext4 /dev/loop0
now you can mount it using
4. mount /dev/mapper/newhome /home/username
or you could use
1. losetup -e aes /dev/loop0 /newfile
2. mkfs -t ext4 /dev/loop0
3. mount -o loop,encryption=aes /newfile /mount_point
You can simple copy the encrypted file into the dropbox folder and mount it from there.
I plan to write an article on encryption soon…:)

By: fatguppy

fatguppy — Mon, 29 Aug 2011 14:55:40 +0000

I mean in what situation would warrent the use of a file as a storage device for daily use?

Does it reduce disk fragmentation? Does it make consolidation of files for backup simpler?

For testing, I assume it makes sense to create file and dump different file systems for experimentation.

By: animaletdesequia

animaletdesequia — Sat, 27 Aug 2011 22:24:16 +0000

Really interesting post, didn’t even know this was possible. Using ubuntu for three years and it still amazes me all you can learn.

I’d like to know how would you modify these steps to create an ext4 with encription and password to decript it. When you install some distros you have the option to encrypt your home file system, so it should be posible to do the same with this kind of files, am I wrong?

My idea would be to put this file into dropbox, and mount it somewhere else (outside dropbox) so I can sync the content of that “folder” trough the cloud without worrying about privacy.

That will be the solution I’ve been serching to create an encrypted folder inside my dropbox where to put sensitive stuff. Sorry if the explanation isn’t really clear, my english is not very good.

Thanks in advance!

By: flossstuff

flossstuff — Sat, 27 Aug 2011 14:48:03 +0000

Hey
Unable to understand you?? Can you be more specific about it?? A brief will be good

By: fatguppy

fatguppy — Sat, 27 Aug 2011 08:25:49 +0000

What use case would be suitable for this method ?

Normally I use TrueCrypt but the container is not expandable once created.

By: flossstuff

flossstuff — Sat, 27 Aug 2011 05:27:16 +0000

We have answered your query above as well as at http://flossstuff.wordpress.com/2011/08/27/how-to-extend-size-of-the-file/

By: adrian

adrian — Wed, 10 Aug 2011 12:25:20 +0000

is possible to extend the size on the ‘filename’ file?

thanks