Hello,
Minor page faults can be harmless, it might just be an indication of the OS going about its regular business. If they are not seeing a degradation in the number of ops then I would suggest you to monitor but not take any action.
If it is associated to a performance degradation in the number of ops I would take a closer look at their memory setup, how much RAM they have, how much they have attributed to Couchbase and how much if any swap they are using.
I cannot explain the difference between 2.0.1 and 2.1.1.
Regards
Tug
@tgrall