I've ran into this problem on a larger scale but lacked the time to investigate it. Now I'm seeing smaller examples on a larger scale and have decided to try to figure it out.

These two computers were imaged from the same DMG and have been in use for a few months. Users have their home folder on another partition, allowing me to nuke the OS partition and reimage it without affecting user data. So nothing the (non-admin) users do should be able to make much of an impact on usable space. My having partitioned the drives (SSDs) means I have a hard limit on space on the system volume, and I'm trying to not use more than I have to, so more is available for the user home folders on the other partition.

This computer has 17gb free:

Code:
df -ht /
Filesystem     Size   Used  Avail Capacity  iused   ifree %iused  Mounted on
/dev/disk0s2   93Gi   75Gi   17Gi    82% 19826055 4555238   81%   /

du -shx *
4.0K	 image.txt
 47G	Applications
436K	Creative Cloud Files
4.0K	DeployStudio_log.txt
9.4G	Library
1.0K	Network
5.1G	System
4.0K	User Information
4.0K	Users
2.3G	Users_old
4.0K	Volumes
2.3M	bin
4.5K	dev
4.0K	etc
1.0K	home
4.0K	installer.failurerequests
1.0K	net
1.3M	opt
4.5G	private
1.1M	sbin
4.0K	setup.xml
  0B	t
4.0K	tmp
608M	usr
4.0K	var


This computer has less than 8gb free:

Code:
df -h /
Filesystem     Size   Used  Avail Capacity  iused   ifree %iused  Mounted on
/dev/disk0s2   93Gi   85Gi  7.7Gi    92% 22352334 2028959   92%   /

4.0K	 image.txt
 47G	Applications
436K	Creative Cloud Files
4.0K	DeployStudio_log.txt
9.5G	Library
1.0K	Network
4.8G	System
4.0K	User Information
4.0K	Users
2.3G	Users_old
 52K	Volumes
2.3M	bin
4.5K	dev
4.0K	etc
1.0K	home
4.0K	installer.failurerequests
1.0K	net
1.3M	opt
4.5G	private
1.1M	sbin
4.0K	setup.xml
  0B	t
  0B	tm
4.0K	tmp
608M	usr
4.0K	var


The question is... WHY? Where did 10 gig of disk space go?

Removing folders with less than 100MB makes it easier to compare

Code:
17GB available:
 47G	Applications
9.4G	Library
5.1G	System
2.3G	Users_old
4.5G	private
608M	usr

8GB available:
 47G	Applications
9.5G	Library
4.8G	System
2.3G	Users_old
4.5G	private
608M	usr


There is a VERY small increase in used space, a few hundred MB, but it's showing a total difference of 10GB.

My only current theory on this is there's a folder somewhere that has a lot of small files in it, and it's the folder size causing this problem. The last time I ran into this, over 100GB of space was missing, and a safe boot fixed it. (and it was NOT due to fsck, I had already repaired the disk, it was deleting temp files or something somewhere)

Ideas?

I work for the Department of Redundancy Department