What kind of FileSystem do you recommend for USB Flash Drive?

Question

This is a problem I'm having when using Ubuntu: I have two computers that have Ubuntu installed on them (comp1 and comp2). I create a document with Ubuntu on comp1 and then copy the file onto a FAT formatted USB flash drive. Via the flash drive I paste the document onto comp2. The problem is that the file-permissions are never preserved during the transfer. I'm assuming because the FAT is not supporting the permissions.

Is there a solution to this? Should I continue to use FAT file system for USB flash drives (because FAT is best for flash drives) and just live with this permissions issue? Or is it recommended to reformat my flash drive with a more "Ubuntu Friendly" file system that will preserve the permissions?

Answer 1

ext4 is a journalling filesystem which means that if the device is unplugged prematurely it stands more of a chance of recovering the damaged filesystem. The journal part of the write contains information about what is about to be done and it gets cleared after the operation is completed. If it is found that there is an uncompleted journal on a device when it is mounted, the filesystem can be reverted to it's previous state thereby preserving its integrity.

While there is some extra overhead in terms of space involved in having a journalling filesystem on a USB stick, it's actually a good choice for most things.

Obviously, if you need a device that can also plug into any computer at any time then FAT would be the way to go. If you want a device that needs to be plugged into one Windows computer only occasionally, then it's possible to install ext2 device drivers in Windows that will allow it to read any and all ext(x) drives. Of course, since Windows doesn't know about Linux permissions and ownership these will not be handled as well.

Answer 2

When using a filesystem which preserves user IDs on a USB drive you may face problems caused by the fact that user IDs are assigned in the order user accounts are created, and the filesystem actually stores numeric IDs of file owners, not usernames. So if, say, machine A has alice and bob accounts, and machine B has bruce, zoe and alice accounts then it likely that when Alice copies her files to an ext(2/3/4)-formatted USB drive, walks to machine B and tries to access the files she will discover that the files are all owned by bruce and are read-only for alice.

Of course, if you only have one user on both machines then this won't be a problem.

Transferring files packed in a tar archive, as proposed by @FSMaxB may solve this problem because when you unpack an archive the files will be created owned by your user ID.

Answer 3

If you use your flash drive only with linux systems, you may use one of the ext-filesystems e.g. ext4 but when using with other systems, FAT is the only compatible file system.

One way of using FAT and preserving permissions (not ownership) would be the usage of tar-Archives!

Answer 4

I'm using reiserfs for years on USB-Sticks without problems. Well - just that they aren't readable from windows systems which might not be bad, if they get lost.

If you partition a stick, to use parts with Windows for data exchange, make sure the windowspartition is the first one - else it won't be identified (at least for XP I made the experience).

You can build a fat-filesystem (aren't they pretty limited for todays stick sizes?) and add an big but empty file to it, and mount that file as a loop device in Ubuntu. Then you will be able to preserve your file permissions, and to increase or decrease the reserved space without partitioning or formatting.

As already mentioned: Tars, Zips and so on are another possibility.