Questions[file-size](ubuntu)

I have a qcow2 file on my filesystem and I am trying to find the size of that file.

For this, when I do a ls -l in the location where the file is stored, I get 13041664, which means the file size is around 13 MB and when I do a file <filename>, I get:

disk: QEMU QCOW Image (v2), has backing file (path 
/var/lib/nova/instances/_base/035db99541e92b5cca93bf18a997d626f), 21474836480 bytes

which, I presume, says the filesize is around 21 GB.

Is this my misinterpretation of the command output or is something else going on inside the filesystem(thin provisioning kind of thing)?

UPDATE: When I do a ls -l on var/lib/nova/instances/_base/035db99541e92b5cca93bf18a997d626f, I get a ls: cannot access /var/lib/nova/instances/_base/035db99541e92b5cca93bf18a997d626f: No such file or directory and its correct that I have no file there

UPDATE 2: The output of qemu-img info <filename> is as follows:

image: disk
file format: qcow2
virtual size: 20G (21474836480 bytes)
disk size: 12M
cluster_size: 65536
backing file: /var/lib/nova/instances/_base/035db99541e92b5cca93bf18a997d626f512b73d (actual path: /var/lib/nova/instances/_base/035db99541e92b5cca93bf18a997d626f512b73d)

The /var/lib contains some unreadable contents, one of which is the mysql folder. I wanted to see the size of the /var/lib folder and the mysql folder in particular. Right-clicking on it and clicking on the "Properties" option gives me this:

In case you need the specs:

• Ubuntu 12.10
• Nautilus 3.4.2

EDIT:

`du -sh /var/lib` gives me this:
du: cannot read directory `/var/lib/sudo': Permission denied
du: cannot read directory `/var/lib/tor': Permission denied
du: cannot read directory `/var/lib/udisks2': Permission denied
du: cannot read directory `/var/lib/php5': Permission denied
du: cannot read directory `/var/lib/openfire': Permission denied
du: cannot read directory `/var/lib/gdm': Permission denied
du: cannot read directory `/var/lib/lightdm': Permission denied
du: cannot read directory `/var/lib/polkit-1': Permission denied
du: cannot read directory `/var/lib/mysql': Permission denied
du: cannot read directory `/var/lib/libvirt/qemu': Permission denied
du: cannot read directory `/var/lib/libvirt/sanlock': Permission denied
du: cannot read directory `/var/lib/libvirt/images': Permission denied
du: cannot read directory `/var/lib/libvirt/boot': Permission denied
266M    /var/lib

and sudo du -sh /var/lib gives this:

309M    /var/lib

When checking the properties of my Downloads folder I saw that it said

Total Size on Files: 5.3GB Size on Disk: 43.0GB

o__O I have noticed this in Windows, but I've been too lazy to inquire further because the difference was only a few percentage. Is this because of the different file system that Linux uses? Is this normal?

I'm trying to archive files with tar and ignoring files larger than 100MB. Is that possible?
PS: Not have to use tar.

I would like to know if it's possible to display the current folder size (in MB or GB) in Nautilus at the status bar.

Here's a screenshot:

as you can see, (in this case) I have 7 items, and I have 125.7 GB left. I would like to display:

7 Items, Folder size: 412 MB, Free space: 125.7 GB

Is it possible? If so how?