ZFS volume does not seem to free space for deleted files

[Matthew D. Fuller]

On Tue, Jul 14, 2015 at 11:49:17AM +0200 I heard the voice of
accounts-ag, and lo! it spake thus:
> 
> So according to my calculation it is using less than 20GB of space
> for snapshots. Which does not make much sense to me as I clearly do
> expect the deleted files to show up somewhere (I did it on
> 2015-07-13). So how can the big difference to USED be explained
> which reports 116G in total?

I'm pretty sure you can't just add up those USED's and get a number
suggesting how much space deleting them all will free up.  AIUI, the
USED number for a snapshot means how much that one alone is using;
e.g., how much space would be freed by deleting just that one.  So any
blocks referenced by 2 or more wouldn't show up in those numbers.  A
bunch of files that have been sitting around a long time would be a
good candidate for existing in most (/all) of them, so you won't see
them in per-snapshot USED until you delete all but 1.


-- 
Matthew Fuller     (MF4839)   |  fullermd at over-yonder.net
Systems/Network Administrator |  http://www.over-yonder.net/~fullermd/
           On the Internet, nobody can hear you scream.