Sorry, was very busy the last weeks.
Finally, I had now time to do some tests:
Created a new (thin, zero-detect) VV (size 10 GB), exported to linux host (SLES 11 SP3) with lvm and ext3 filesystem. Separated into 2 LVs with 5 GiB each.
Allocation: 2,250 GiB (1 GiB User Space, 1 GiB Copy Space, 0,250 GiB Admin Space)
Copied a zero-filled 2GB file -> didn't reclaim any space on 3PAR as expected.
Deleted that file, copied a 2 GB file with random data -> reclaimed additional 3 GB (User Space) on 3PAR (yes three GiB). Hm, okay...
Deleted that file -> spaces stays allocated.
Did a fstrim on that volume -> spaces stays allocated.
Created (dd) a 5 GiB zero-file on that volume -> spaces stays allocated (but doesn't increase).
Compact CPG doesn't work ("CPG is already compacted"). Any way to get that space back on 3PAR?
Or do we need AO (tunevv) to get that VV small again?
Btw: When creating a physical copy the copy is thin again, so 3PAR recognize the zero filled space.
Maybe it's just some problem with ext3 or SLES? Unfortunatly, ext4 isn't supported (only readonly), so I can't check that.