[CentOS] Invisible files and disk space

Thu Oct 8 16:31:34 UTC 2020
centos2 at foxengines.net <centos2 at foxengines.net>

On Thu, Oct 08, 2020 at 11:12:54AM -0400, Yves Bellefeuille wrote:
> centos2 at foxengines.net wrote:
> > It's not working, I haven't been able to identify the files. They
> aren't
> > there. All attempts to measure disk usage of / by files shows that the
> > disk usage is only a percentage of available space and that there
> > should be space available.
> Sparse files? How are you determining how much free space you have?

Thanks for your response.

I didn't attempt to find sparse files specifically but there were no files (or
dot-files) at the top level of / that contained any significant data.

There sum of the sizes of all of the directories at the top level of / reported
by du did not match the amount of disk space used at the time of the problem.
I don't have a transcript of that session but I was using commands like:

find / -maxdepth 1 -xdev -type d | while read; do du -shx $d; done

I poked around in /var and /tmp a lot but didn't find anything that would
contradict the output of the previous command.

At this point I started searching for deleted files for which the space had not
been reclaimed. Finding nothing I though there was something I hadn't run into
before and didn't know what to look for.

I'm not confident I understand your meaning in the second sentence. I didn't
try to determine how much free space I had because there wasn't any.
The root filesystem was at 100% capacity and services were failing. I was just
trying to find out what had taken it all since normal usage is around 33% or
so, according to df.
Rebooting the computer eliminates the problem. When it comes back up, the disk
usage is again at 33%. Whatever it is, vanishes during a reboot.