To whom it may concern,

I have a problem that election happens frequently on primary shard in　sharded-cluster. These elections seem to happen in accordance with the failures of heartbeats between primary and secondary although there doesn't seem to be any network problems. Neither the network traffic nor the amount of connections is far from limits(traffic: 5Mbps to 15Mbps, connections: 30 to 60).

Heartbeat has been continuously failing. As the probable result of it, election happens as well from 10 to 20 times a day on the primary shard, while once or twice at the most on the other normal shards.

Is there any good way to stabilize the primary shard status? Our application fails every time the election happens and then it has to wait until a new primary is elected.

This problem significantly affects our application performance. I would appreciate if you could give me any help to solve it.

Best Regards,
Kazuo Yagi <ka_yagi@fancs.com>

• Our sharded cluster has 10 shards each of which consists of 1 primary, 1 secondary and 1 arbiter.Therefore, the amount of hosts is 30.
  Each member's priority is 1(= default value).The mongodb version is 2.6.6 for ubuntu 14.04, amd64 architecture. All hosts are running on AWS.