Keep Mongo DB set up up and running with two data center always

Question

There is a scenario where we have 5 member replica set across two data centers.
Data center 1 : 3 Members
Data center 2 : 2 Members
Situation is if DC 1 goes down DC 2 becomes read only but we need to keep it ready to accept writes also.
Is there any possibility for same using one extra member like hidden node or two arbiter.
We do not have third data center.

Thanks
Virendra Agarwal

Answer 1

With two DC's "getting working solution" it's always something "not recommended for mongodb". That third DC is not a big deal. It is just arbiter in some XS size VPS what will cost you 15€/year. Like http://www.time4vps.eu So, working solution is 4 data bearing node and one arbiter (2+2+1). One DC can always go down and replica set still keeps serving.

Answer 2

This is a configuration will work with using Virtual Host Names for config and arbiters. When you bring up the hidden ones you only need to change DNS entries to point to DC2 servers.