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Author few thoughts on creating a virtual file system
Mike Chirico

2004-01-23, 5:06 pm

I just wanted so share a few thoughts here on creating a virtual file
system.

I move around from computer to computer, and it's nice to have access to all
my files, along with the symbolic links etc. So what I did was create a
file and mounted it as a drive. Then, when I moved to another computer for
a few hours, I just copied the file and mounted in again on the second
computer. True, I could have used ssh; but, it was kind of nice to have the
speed of accessing it locally. Anyway, it works well for me...these are the
steps I use:

1. Construct a 10MB file, or bigger:

dd if=/dev/zero of=/tmp/disk-work count=20480

By the way, dd defaults to blocks of 512 so the above will = 10MB =
20480*512. The "if=/dev/zero" stand for read from file, and /dev/zero will
zero everything out. As you can probably guess, "of=/tmp/disk-work" creates
the file. You should probably create it in your home directory
"of=/home/<your name>/disk-work" since you'll have more space and it won't
get deleted.

2. Make an ext2 (or ext3 if you want) file system. I believe the difference
is ext3 is a journaling filesystem; but, it doesn't handle recovery as well
as ext2.

mke2fs -q /tmp/disk-work

Hit yes for confirmation, and it's going to ask this because it's a file and
not a drive.

3. Create a directory, su -l to root, and mount.

mkdir /work
su -l
mount -o loop=/dev/loop0 /tmp/disk-work /work

Now to use it, cd /work and create files etc.

4. When you're done with it, unmount

umount /work


What's nice is it's mounted similar to a drive. A "lost+found" directory is
created. In addition, if more drives are needed, use /dev/loop1, /dev/loop1
etc. By the way, CD-ROM's can be copied to a file and mounted as well for
faster access.

Regards,

Mike Chirico


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