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I have a flash drive which is FAT32 formatted. I want to put a linux filesystem on the drive inside a file. I know I can do this by creating a file and formatting is with ext3 (or any other file system) and then mounting it with the -o loop option. What I would like is that the above filesystem be compressed. Essentially something like a read-write squashfs.

Is there something that exits that I can use? Additional bonus if the file can be stored as sparse, i.e. the file re-sizes as data is written or deleted.

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migrated from serverfault.com Dec 1 '11 at 0:34

This question came from our site for system and network administrators.

I don't know enough to put this as an answer but looks like squashfs could be what you are looking for. – phunehehe Dec 1 '11 at 2:37
up vote 7 down vote accepted

Write a .7z, .tgz, .zip or other compressed archive file.

Bonus: you can read it anywhere.

Downside: it can be slow if you have a lot of files.

Use avfs to access files inside the archive transparently.

mount /dev/my_flash_drive /media/flash0
rsync -au mydata/foo/ ~/.avfs/media/flash0/archive.tgz\#/foo/
umount /media/flash0
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ooh, that's very nice. i'm going to be using that. – ixtmixilix Dec 1 '11 at 11:08

BTRFS has a compression mode built-in, but with the correct mount option. And the file must be at the final size. As BTRFS can resize the partition on-the-fly it could be possible to hack something for increasing the file, but I never tried and I won't try it.

But the best way would be to buy a bigger flash drive than hacking around with compression.

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Thanks a lot. Part of the problem is that I am limited by the 2GB file size of FAT32. Maybe its time to put NTFS on the flash drive. – Doc Dec 1 '11 at 3:46

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