Unix is not my native language and I'm getting confused by their concept of filesystems.
When I look at my free space I see:
/$ df -kh Filesystem Size Used Avail Use% Mounted on /dev/xvda1 7.9G 7.1G 397M 95% / none 3.7G 120K 3.7G 1% /dev none 3.7G 4.0K 3.7G 1% /dev/shm none 3.7G 48K 3.7G 1% /var/run none 3.7G 0 3.7G 0% /var/lock /dev/xvdf 100G 19G 82G 19% /db /dev/xvdg 100G 15G 86G 15% /images /dev/xvdb 414G 199M 393G 1% /mnt
To me this means all files and directories under /db is on filesystem xvdf, everything under /images is on xvdg and everything under /mnt is on xvdb. Everything else is on xvda1.
However, xvda1 has only 7.9G of space. So why does
/$ sudo du -sh var 25G var
show me that /var is taking up 25G? I thought at first that maybe it's counting the contents at the destinations of symbolic links but I know a few directories down there's a symbolic link to the /images directory and that's got 86G of content so var should be >86G if symbolic links are followed.
So how can /var take up 25G on a drive that has only 7.9G?
btw, this is an ubuntu instance running in amazon's EC2, if that's significant.