Re: hard-link question

[Gary Dale <garydale@rogers.com>]

On 28/07/12 03:08 PM, Umarzuki Mochlis wrote:
> this output is before i hard-linked a 4.4 MB mp3 file
>
> $ df
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/sda2            677688728 112432972 531334324  18% /
> tmpfs                  1987692         0   1987692   0% /lib/init/rw
> udev                   1981764       244   1981520   1% /dev
> tmpfs                  1987692         4   1987688   1% /dev/shm
> /dev/sda1               297560     49172    233028  18% /boot
>
> this is after hard-linked that file
>
> umarzuki@v470:~/Videos$ df
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/sda2            677688728 112432940 531334356  18% /
> tmpfs                  1987692         0   1987692   0% /lib/init/rw
> udev                   1981764       244   1981520   1% /dev
> tmpfs                  1987692         4   1987688   1% /dev/shm
> /dev/sda1               297560     49172    233028  18% /boot
>
> this is after I deleted the original mp3 file
>
> umarzuki@v470:~/Videos$ df
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/sda2            677688728 112432996 531334300  18% /
> tmpfs                  1987692         0   1987692   0% /lib/init/rw
> udev                   1981764       244   1981520   1% /dev
> tmpfs                  1987692         4   1987688   1% /dev/shm
> /dev/sda1               297560     49172    233028  18% /boot
>
> i can still play the mp3 file.
Of course. A hard link is basically the same as a directory entry 
pointing to the file.

> Why is that the used space is reduced (/dev/sda2) after I hard-linked
> that mp3 file?
> Why is that the used space is increased after I deleted the source mp3 file?
Could be something to do with the file system being used. The journal, 
for example, might shrink or grow. It may have little or nothing to do 
with the hard linking.