Installing GNU/Linux on a FAT Drive – Feasibility and Steps

fatfat32filesystemsroot-filesystemvfat

Out of curiosity, is this possible nowadays? I remember some old Slackware versions did support FAT root partition but I am not sure if this is possible with modern kernels and if there are any distros offering such an option. I am interested in pure DOS FAT (without long names support), VFAT 16/32 and exFAT.

PS: Don't tell me I shouldn't, I am not going to use this in production unless necessary 🙂

Best Answer

OK, I tried it.

First two problems from the beginning: NO support for hard and symbolic links. It means that I had to copy each file, duplicating it and wasting space.

Second problem: no special file support at all. This means things like /dev/console are unavailable at boot time to init before even /dev is remounted as tmpfs.

Third problem: you will loose permissions enforcing.

But out of this, there were no issues. My own system was booted successfully on a vfat volume.

Normally I would not do that, too.

Related Solutions

Change file creation time on a FAT filesystem

First thing that comes to mind is to mv the file(s) to a temporary, cp the temporary file to the old filename and delete the temporary.

I just made a fast check:

touch foo
ls -l foo

returns:

0 -rw-r--r-- 1 shunz shunz 0 2011-03-22 11:07 foo

wait some minutes and then:

mv foo bar
ls -l bar

0 -rw-r--r-- 1 shunz shunz 0 2011-03-22 11:07 bar

notice the creation time isn't modified, while:

cp bar foo
ls -l foo bar

0 -rw-r--r-- 1 shunz shunz 0 2011-03-22 11:07 bar
0 -rw-r--r-- 1 shunz shunz 0 2011-03-22 11:10 foo

now foo is created at current time!

EDIT

sorry, forgot to mention, tried this on a FAT32 formatted USB stick under Ubuntu.

A clever way to defragment a FAT filesystem

You can check whether a file is fragmented or not using the filefrag utility.

That way you could filter out the files that aren't fragmented, and do the copy/copy back only for already fragmented files. That should save you some time. However be aware that there is no guarantee the new file layout will be better than the old one.

The best way is to ignore file fragmentation altogether. Especially on a USB stick it hardly matters, only wastes write cycles, and unlike HDDs, there are no movable parts and thus not much of a penalty due to fragmentation.

Defragmentation should only be necessary if something funny happened that caused files to fragment in a very extreme way. For example torrent clients that download file contents in random order without preallocating. But unless FAT started supporting sparse files at some point that's not even an issue there, as preallocating is mandatory on such a FS.

Best Answer

Related Solutions

Change file creation time on a FAT filesystem

A clever way to defragment a FAT filesystem

Related Question