Another option that is built into the kernel is LXC (LinuX Containers). It's not full virtualization like KVM, but it's nice and lightweight. It's similar to OpenVZ if you have any experience with that. Here's a link: http://wiki.centos.org/HowTos/LXC-on-CentOS6
That's one of the first things I thought about (I used to work for a company that writes backup software and this came up a lot) so I researched it to refresh my memory. The filesystem (ext2, ext3, ext4) reserves about 5% for a buffer zone by default, which is nowhere near the 20ish percent that our OP is seeing.
This does come up a lot on larger filesystems. Since the default is 5%, you lose about 50GB on a 1TB partition, or 400GB on an 8TB partition. But 5% of 20GB is only 1GB. You usually notice the difference in the space remaining in your 'df' output, but 'du' output should be correct. I suspect that whats being reported is actually correct, but we aren't seeing all the numbers.
Hidden files should be included in du output. I'm not familiar with ncdu, but I'm checking it out now!
What do you get from this command: sudo du -sh /
And I guess ncdu works based on du. Its just more user friendly. From that command I get:
sudo du -sh /
[sudo] password for darius:
du: cannot access `/proc/10549/task/10549/fd/4': No such file or directory
du: cannot access `/proc/10549/task/10549/fdinfo/4': No such file or directory
du: cannot access `/proc/10549/fd/4': No such file or directory
du: cannot access `/proc/10549/fdinfo/4': No such file or directory
hmm,then its interesting why ncdu would not include hidden files space. And btw probably thre is no recycle bin (I guess) because its without graphical enviroment, its only console. Its in anohter server.
It could also be that it's actually just a mathematical problem with the computer. You see, most people view 1 GB as 1000 MB. In reality, it's 1024 (computers do everything in binary, which is powers of 2). This 24 mb adds up with each GB. And really, if you look at it that way it's even larger. Basically, the right click on the drive telling you the specs and the space are calculated as 1000mb per Gb. It's not gone, just not showing it to you correctly.
That in conjunction with the MBR (master boot record) and the paging file plus the reserved space for the recycle bin can add up. The paging file can range anywhere from a couple hundred MB to a couple GB (depending on how big your filing system is). All that adds u [Sometimes].
i have implemented new passwd policy and forced users to change their password the proble is they dont know what they should insert as new password. i want to display a message like this one "passwd minimum length 8, must have 1 upper, 1 lower, 1 digit) or something like this instead of "BAD PASSWRD: its WAY too short" ... any help will be appreciated
tnx in advance