Basic Replication Setup with Arbiter
Arbiter
- Arbiters are mongod instances
that are part of a replica set
- It does not hold any data
- It only participates in election during
failover
- If a replica set has an even number of members,
add an arbiter
- Arbiters have minimal resource requirements and
do not require dedicated hardware.
Let’s see an example with Arbiter
Servers:
ec2-34-228-80-121.compute-1.amazonaws.com - data
ec2-54-147-246-184.compute-1.amazonaws.com - data
ec2-54-243-20-99.compute-1.amazonaws.com - Arbiter
Note:
- Please follow the same steps which is mentioned
in the previous post Basic Replication Setup till adding replica set member.
- Config file also as same as the replica set
member
- There will a small change in adding an Arbiter
Assuming that all 3 servers are up and running
Connect a mongo shell to one of the mongod instances.
ec2-34-228-80-121.compute-1.amazonaws.com
# mongo
Initiate
the replica set.
# rs.initiate()
Add the
Replica Set Members
# rs.add(“ec2-54-147-246-184.compute-1.amazonaws.com:27017”)
# rs.addArb(“ec2-54-243-20-99.compute-1.amazonaws.com:27017”)
View the
replica set configuration.
# rs.conf()
Here you
can see arbiterOnly : true in the Arbiter node
learning:PRIMARY>
rs.conf()
{
"_id" : "learning",
"version" : 5,
"protocolVersion" :
NumberLong(1),
"members" : [
{
"_id" : 0,
"host" :
"ip-172-31-29-148.ec2.internal:27017",
"arbiterOnly"
: false,
"buildIndexes" : true,
"hidden" : false,
"priority" :
1,
"tags" : {
},
"slaveDelay"
: NumberLong(0),
"votes" : 1
},
{
"_id" : 1,
"host" :
"ec2-54-147-246-184.compute-1.amazonaws.com:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" :
false,
"priority" :
1,
"tags" : {
},
"slaveDelay"
: NumberLong(0),
"votes" : 1
},
{
"_id" : 2,
"host" :
"ec2-54-243-20-99.compute-1.amazonaws.com:27017",
"arbiterOnly" : true,
"buildIndexes" : true,
"hidden" :
false,
"priority" :
1,
"tags" : {
},
"slaveDelay"
: NumberLong(0),
"votes" : 1
}
],
"settings" : {
"chainingAllowed" :
true,
"heartbeatIntervalMillis" : 2000,
"heartbeatTimeoutSecs" : 10,
"electionTimeoutMillis" : 10000,
"getLastErrorModes" :
{
},
"getLastErrorDefaults" : {
"w" : 1,
"wtimeout" :
0
},
"replicaSetId" :
ObjectId("5aded4fcfbfb90cc683df7b3")
}
}
learning:PRIMARY>
To check the status of Arbiter node
# rs.status()
Here you can find "stateStr" :
"ARBITER" in the Arbiter node
learning:PRIMARY> rs.status()
{
"set" : "learning",
"date" : ISODate("2018-04-24T07:05:17.699Z"),
"myState" : 1,
"term" : NumberLong(1),
"heartbeatIntervalMillis" : NumberLong(2000),
"members" : [
{
"_id" : 0,
"name" :
"ip-172-31-29-148.ec2.internal:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" :
588,
"optime" : {
"ts"
: Timestamp(1524553218, 1),
"t" :
NumberLong(1)
},
"optimeDate"
: ISODate("2018-04-24T07:00:18Z"),
"electionTime" :
Timestamp(1524552956, 2),
"electionDate" : ISODate("2018-04-24T06:55:56Z"),
"configVersion" : 5,
"self" : true
},
{
"_id" : 1,
"name" :
"ec2-54-147-246-184.compute-1.amazonaws.com:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 308,
"optime" : {
"ts"
: Timestamp(1524553218, 1),
"t" :
NumberLong(1)
},
"optimeDate"
: ISODate("2018-04-24T07:00:18Z"),
"lastHeartbeat" :
ISODate("2018-04-24T07:05:16.512Z"),
"lastHeartbeatRecv" :
ISODate("2018-04-24T07:05:16.512Z"),
"pingMs" :
NumberLong(0),
"syncingTo" :
"ip-172-31-29-148.ec2.internal:27017",
"configVersion" : 5
},
{
"_id" : 2,
"name" :
"ec2-54-243-20-99.compute-1.amazonaws.com:27017",
"health" : 1,
"state" : 7,
"stateStr" : "ARBITER",
"uptime" :
299,
"lastHeartbeat" :
ISODate("2018-04-24T07:05:16.511Z"),
"lastHeartbeatRecv" :
ISODate("2018-04-24T07:05:13.468Z"),
"pingMs" :
NumberLong(0),
"configVersion" : 5
}
],
"ok" : 1
}
learning:PRIMARY>
Done…
