## 11.6.12 What information do arbiters exchange with the rest of the replica set? 

Arbiters never receive the contents of a collection but do exchange the following data with the rest of the replica set: 

• Credentials used to authenticate the arbiter with the replica set. All MongoDB processes within a replica set use keyfiles. These exchanges are encrypted. 

• Replica set configuration data and voting data. This information is not encrypted. Only credential exchanges are encrypted. 

If your MongoDB deployment uses TLS/SSL, then all communications between arbiters and the other members of the replica set are secure. See the documentation for Configure mongod and mongos for TLS/SSL (page 342) for more information. Run all arbiters on secure networks, as with all MongoDB components. 

## See 

The overview of Arbiter Members of Replica Sets (page ?? ). 

## 11.6.13 Which members of a replica set vote in elections? 

All members of a replica set, unless the value of votes is equal to 0 , vote in elections. This includes all delayed (page 570), hidden (page 569) and secondary-only (page 567) members. Arbiters (page ?? ) always vote in elections and always have 1 vote. 

Additionally, the state of the voting members also determine whether the member can vote. Only voting members in the following states are eligible to vote: 

• PRIMARY 

• SECONDARY 

• RECOVERING 

• ARBITER 

• ROLLBACK 

## See also: 

Replica Set Elections (page 580) 

## 11.6.14 Do hidden members vote in replica set elections? 

Hidden members (page 569) of replica sets do vote in elections. To exclude a member from voting in an election , change the value of the member’s votes configuration to 0 . 

## See also: 

Replica Set Elections (page 580) 

## 11.6.15 Is it normal for replica set members to use different amounts of disk space? 

Yes. 

Factors including: different oplog sizes, different levels of storage fragmentation, and MongoDB’s data file pre- allocation can lead to some variation in storage utilization between nodes. Storage use disparities will be most pro- nounced when you add members at different times. 

