Error on adding an arbiter

Question

Adding 5th node getting an error

"Our replica set configuration is invalid or does not include us

Presently all 4 nodes are healthy.

	node	arb1	arb2
rs1	m1,m2,m2	a1

when I try to add a2 both the arbiters will go unhealhty immediately whereas my arbiter is healhty on itself but not healthy in replica set.

	node	arb1	arb2
rs1	m1,m2,m2	a1	a2

Error for arbiter in replica set -

a1 - "lastHeartbeatMessage" : "Our replica set configuration is invalid or does not include us"

a2 - "lastHeartbeatMessage" : "Couldn't get a connection within the time limit"

where,

m- data nodes

a- arbiters

Answer 1

Replica set should have ONLY one arbiter and ONLY when there is an even number of data-bearing nodes.

Your replica set has already an odd number of data-bearing nodes (m1, m2, and m3), so there should not be any arbiters.

Those error messages means:

a1 - rs.conf() don't have that a1 node in the list of that replica sets' config, it may have wrong IP or port-number
a2 - there is firewall (or similar) what prevents connection with other RS nodes.

Answer 2

Use bellow code before adding arbiter to cluster

db.adminCommand(
  {
    setDefaultRWConcern : 1,
    defaultWriteConcern: { w: 1 },
  }
)

After this add arbiter to cluster

rs.addArb("<private-ip>:27017")