How much RAM needs to be given to Active documents in the bucket and how much RAM to OS on Couchbase server Node

How much RAM quota should be allocated to active documents.
Suppose there are 8 million documents in the bucket and out of that 1 million documents are used by N1QL
queries. Other documents are not much used.
Size of 8 million documents is around 20 GB, size of 1 million records (active documents) will be 2.5 GB

If RAM size of cluster is 28 GB (2 nodes with 16 GB each, 2 gb given to OS on each node)
Then how much percentage of RAM needs to be allocated to the active documents
In other words what is preferred values for mem_high_wat and mem_low_wat

Also how much memory should be given to OS, 2 GB on each node is sufficient for Linux
or need more RAM.


I think this link will give you same guidance.