Strange thing with filesystem

[sybvn]

Hi all,

I see some strange thing in my file system. I can't say it have occured or it is just file system properties because I've never notice it before.

I make a file system by the following process which is common to us:

(1)
dd if=/dev/zero of=./initrd bs=1k count=5632
mke2fs -F -m0 ./initrd

(2)
Mount and copy files into it:
mount -o loop ./initrd ./root
cp <somefiles> ./root
umount ./root

(3)
Then I gzip it for some purpose
gzip -v9 < ./initrd > ./initrd.gz

I see that, if I just do step (2) with only mout and umount without any change on the initrd, but gzip in step (3) produce different file size each time I do the command (It happen that I don't know how to show the real size of filesystem content except using df command which display used size in percentage which doesn't show any difference when there is minor change in rootfile system content size. I think gzip is something by which I can know about the filesystem real size). The difference is about 2 bytes to 8 bytes. Could someone tell me how this happened?

Thanks

[scm]

Can you post the outputs of the two commands you're running so we can see the actually values? What does "ls" show the file sizes to be?