Hi, there are many different ways how to setup and use dedupe. Here are just 2 of it
Example 1:
Set up a 100GB LUN spacereserved and a 200GB volume to space guarantee volume.
Without dedupe:
Aggr = Total:1000GB Free:800GB
Volume = Total:200GB Free:100GB
LUN = 100GB
With dedupe 50% saved:
Aggr = Total:1000GB Free:800GB
Volume = Total:200GB Free:150GB
LUN = 100GB (50%/50GB saved by dedupe)
As you see the dedupe saves 50GB and give it to the Volume but not to the Aggr. You can use the saved space to setup an additional LUN in your Volume.
Example 2:
Set up a 100GB LUN spacereserved and a 200GB volume to space guarantee none.
Without dedupe:
Aggr = Total:1000GB Free:900GB
Volume = Total:200GB Free:100GB
LUN = 100GB
The Aggr freespaces changed cause the Volume just reserve the space of the 100GB LUN
With dedupe 50% saved:
Aggr = Total:1000GB Free:950GB
Volume = Total:200GB Free:150GB
LUN = 100GB (50%/50GB saved by dedupe)
Instead of example 1 now the Aggr freespace also changed and you can use it for additional Volumes
The spacereserved options does not change your dedupe results. If we look again to example 2, It doesn't matter if the LUN is spacereserved or not the amount of saved space would be exactly the same cause dedupe is volume based. Here is what spacereservation does:
Example 1: We install Windows at our 100GB spacereserved LUN and our 100GB Windows partition uses 20GB of Space. The Volume is still 200GB and spacereserved none.
AGGR = Total:1000GB Free:900GB
Volume = Total:200GB Free:100GB
LUN = 100GB
Example 2: We install Windows at our 100GB !!NOT!! spacereserved LUN and our 100GB Windows partition uses 20GB of Space. The Volume is still 200GB and spacereserved none.
AGGR = Total:1000GB Free:980GB
Volume = Total:200GB Free:180GB
LUN = 100GB
As you see the hole filer just reserve the space that Windows actually uses
So in my opinion the best option is to set up the Volume to space guarantee none and use the new free space for additional volume.