I have a 3-node replica set: one is primary and the other two are secondaries. Originally my mongoid.yml has this:

hosts:
    - 10.4.6.66:27017 (this is the primary)
options:
    consistency: :strong

Everything is fine, even in the mongodb side, it is already a replica set. Then I changed my mongoid.yml to reflect the replica set change:

I have a 3-node replica set: one is primary and the other two are secondaries. Originally my mongoid.yml has this:

hosts:
    - 10.4.6.66:27017 (this is the primary)
    - 10.4.4.35:27017
    - 10.4.2.4:27017
options:
    consistency: :eventual

Then I started to get a lot of 500 errors in my request, and all of them are requests trying to write to the DB.

What is the problem here?

I am using MongoDB 2.4.3, Mongoid 3.1.2, Rails 3.2.x