The other obvious question then - what is the snapshot schedule like? Do you have the volumes running regular snapshots, and how long are they being maintained?
Remember that space determined to be saved due to a compression/dedupe run is logically "deleted" from the volume. However, if you were snapshotting the volume before/during that roughly 5 day initial space efficicency run, all that deleted space is still in the snapshots so you haven't "saved" it yet.
As the snapshots expire, or as you delete them yourself, additional savings will be had. For instance, on a particualr volume I have that is already at 49% dedupe (12TB volume actual, 11TB saved to date, 23TB logical) the most recent run will save an additional 0.7TB in space efficiencies, but that space won't show up for two weeks because it's working through the snapshot retention times.
What does the "vol snapshot show" list for the volumes of interest? Are there snapshots that hold a lot of space?
Hope this helps.
Bob Greenwald
Lead Storage Engineer, Consilio LLC
NCIE SAN Clustered, NCIE Data Protection