I have a ONTAP 8.1.2 device running in 7-mode. I have 3.2 TB of CIFS data with deuplication savings of 720 GB. I suspect I will get more with compression. I have already enabled inline compression, but need to compress existing data.
My understanding of the steps is as follows:
1) Delete all snaphots
2) Turn off active snapshots and nightly deduplication tasks
i think that the compression rate you get on CIFS volume when its fixed block size (not adaptive as avail in Cdot) and without compaction (again only in Cdot) is not great. i see it giving only 16% in my environment before compaction. (i wish to move mine to adpative but don't have much time for that...)
from the TR 3958. you can compress snapshot data as well. it's just comes with a penalty that until the snapshot deleted you end up with the two copies of the block. the compressed one and the non-compress one. if you have spare space - you can do it (but my personal advise that if you do have spare space, don't do it 😄 - and just leave it uncompressed until it ends up on Cdot with adaptive and compaction features)
yes we saw something similar in a test recently...we create a new 200g vol and added 50g of data from our home drives, mashup of small xp files, office stuff , pst, the usual guff.
Dedupe was 1% and compression 12%.
We were disappointed ...the figures for file services in Netapp docs suggest a more dramatic increase...our real volumes are showing 30% dedupe so perhaps thats a good indicator of a better compression rate too.
Probably worth implementing PP anyway ...took note of your comments on whether to do the whole volume if one needs to hang on to snaps.