RAID0 NAS won't free up space after files removed - Otherwise seems OK

I have a Buffalo LS-WX6.0TL (Rev 1.0) working as a home NAS - it has twin 3TB drives in RAID0 It behaves perfectly but it's very nearly full so I've taken around 800GB of data off simply by moving it across to another SATA drive as an archive.

Despite that the free capacity of the NAS obstinately refuses to change and shows just 300GB free (unchanged from before I started off-loading files).  

I've disconnected it, reconnected it, run Buffalo's own web interface checking tools, shouted at and threatened it, yet I cannot get the space I should have created by moving the data to show up.

If I add files to the NAS the available space continues to reduce (!)

What am I missing here?  Is the array damaged somehow?  Any non-destructive repair suggestions?  I'd rather not move 5TB of data (it is backed up to a separate Raid10 but it still means a lot of time to put things back).
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☠ MASQ ☠Asked:
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What type of file-system does it use? If it is something like ZFS or BTRFS it would possibly have kept those files in snapshots.
☠ MASQ ☠Author Commented:
striped twin drives
Although XFS itself doesn't directly support snapshots, it can still be implemented indirectly. I don't know the Buffalo's OS, but it could have been implemented there. Check the interface for any snapshots you could delete. Or maybe also check if there is a firmware upgrade.

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☠ MASQ ☠Author Commented:
Latest firmware (1.60), snapshots not supported.
Then I don't know what else could be the issue.
Can you try rebooting the NAS? In some cases the free space won't show up again until all file handles are closed. Simplest way to accomplish that is to reboot the NAS.
☠ MASQ ☠Author Commented:
Rebooted via web interface
Afterwards same capacity :(
☠ MASQ ☠Author Commented:
Thanks - rindi, you were right on the money - I got hold of Buffalo and they pointed out that their software automatically creates a recycle bin in each partition created in a folder called Trashbox - which effectively is the snapshot you were describing.

Embarrassingly enough the partition I was cleaning up had been created so long ago I was sure that folder was something I'd set-up to clean up earlier and hadn't bothered to check that the contents exactly mirror the folder structure of the partition!

Apologies for not picking up on it earlier!!
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