Replica set members send heartbeats to each other for every two seconds. If a heartbeat does not reach within 10 seconds, the other members mark the member as dead.
Based On
Heartbeats ,Priority Comparisons ,Optime, Connections ,Network Partitions.
Heartbeats
Replica set members send heartbeats to each other every two seconds. If a heartbeat does not reach within 10 seconds, the other members mark the member as dead.
Priority Comparisons
Members will to vote for members who is having highest priority value
Members are not eligible for election. whose priority value is 0 and cannot become primary
Optime
The optime is called as the timestamp of the last operation that a member applied from the oplog.
A replica set cannot become primary unless it has the highest recent optime of any visible member.
Connections
A replica set cannot become primary unless it can connect to a majority total number of votes in the replica set.
If you have a three replica set, where every member has only one vote, the set can elect a primary as long as two members can connect to each other. If two members are dead, the remaining member remains a secondary because it cannot connect to a most of the set’s members. If the remaining is a primary and two members become dead, the primary becomes secondary.
Based On
Heartbeats ,Priority Comparisons ,Optime, Connections ,Network Partitions.
Heartbeats
Replica set members send heartbeats to each other every two seconds. If a heartbeat does not reach within 10 seconds, the other members mark the member as dead.
Priority Comparisons
Members will to vote for members who is having highest priority value
Members are not eligible for election. whose priority value is 0 and cannot become primary
Optime
The optime is called as the timestamp of the last operation that a member applied from the oplog.
A replica set cannot become primary unless it has the highest recent optime of any visible member.
Connections
A replica set cannot become primary unless it can connect to a majority total number of votes in the replica set.
If you have a three replica set, where every member has only one vote, the set can elect a primary as long as two members can connect to each other. If two members are dead, the remaining member remains a secondary because it cannot connect to a most of the set’s members. If the remaining is a primary and two members become dead, the primary becomes secondary.
Network Partitions
Network partitions affect the formation of a most for an election. If a primary becomes down and neither portion of the replica set has a most majority the set will not elect a new primary. The replica set becomes read-only. To overcome this situation, place a majority of instances in one data center and a minority of instances in any other data centers combined.
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