mongod --port 27021 --dbpath /cm1/mongodb/rs0-1 --replSet rs0 --smallfiles --oplogSize 128.

2017-07-25T13:01:24.904+0530 I REPL     [ReplicationExecutor] Error in heartbeat request to localhost:27021; HostUnreachable: Connection refused
2017-07-25T13:01:24.904+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Connecting to localhost:27021
2017-07-25T13:01:24.906+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Failed to connect to localhost:27021 - HostUnreachable: Connection refused
2017-07-25T13:01:24.906+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Dropping all pooled connections to localhost:27021 due to failed operation on a connection
2017-07-25T13:01:24.906+0530 I REPL     [ReplicationExecutor] Error in heartbeat request to localhost:27021; HostUnreachable: Connection refused
2017-07-25T13:01:24.906+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Connecting to localhost:27021
2017-07-25T13:01:24.907+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Failed to connect to localhost:27021 - HostUnreachable: Connection refused
2017-07-25T13:01:24.907+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Dropping all pooled connections to localhost:27021 due to failed operation on a connection
2017-07-25T13:01:24.907+0530 I REPL     [ReplicationExecutor] Error in heartbeat request to localhost:27021; HostUnreachable: Connection refused
2017-07-25T13:01:26.908+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Connecting to localhost:27021
2017-07-25T13:01:26.910+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Failed to connect to localhost:27021 - HostUnreachable: Connection refused
2017-07-25T13:01:26.910+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Dropping all pooled connections to localhost:27021 due to failed operation on a connection
2017-07-25T13:01:26.910+0530 I REPL     [ReplicationExecutor] Error in heartbeat request to localhost:27021; HostUnreachable: Connection refused
2017-07-25T13:01:26.910+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Connecting to localhost:27021
2017-07-25T13:01:26.911+0530 I ASIO     [NetworkInterfaceASIO-Replication-0] Failed to connect to localhost:27021 - HostUnreachable: Connection refused