Question

my mongodb rs configure resemble:

node1:shard1 primary,shard2 primary 
node2:shard1 secondary,shard2 secondary 
node3:shard1 arbiter,shard2 artbite

every time there are many writes and read,but yesterday I found the mode1 become secondary,contrast,node2 become primary,I’m very weird,so post this issue,hoping more opnions.
Thanks in advance

Answer 1

A primary stepping down to become a secondary is not unusual in a Replica Set, and will happen for one of three reasons.

1. It is told to by the replSetStepDown command
2. The primary cannot contact a majority of nodes
3. It sees that a secondary is more eligible to be primary and has a higher priority.

A secondary can also call for an election if it cannot contact a primary, or if the primary is too slow to respond. The election will force the primary to step down.

You can read more about this process in the documentation