Deleted over 4TB on Promise VTrak, still shows as full This is not a duplicate of Why is my hard drive still full after deleting files?

I have of course attempted all methods mentioned there. Via the terminal I can see nothing listed on the drive. I was able to list all the hidden (.named) folders using ls -a | egrep '^\.' which then showed me the expected hidden folders, all of which I sudo rm -rd I've ran a Verify/Repair with Disk Utility (not sure of the effectiveness on an external RAID) but it had no effect.

I know a solution is just reformat, but what if I had a 10TB RAID and still had multiple terabytes of data? Formatting would not be an option.

This is not a locked files issue, not a trash issue, what seams to be the problem?

How can I free up the (4TB, claimed to still be taken up) space on the empty 5TB Promise VTrak E610f media RAID?
This was a production server so I couldn't be too forceful. 

Inevitably, after hours, a reboot resolved the issue. Not my favorite solution by any means.