Distributed Systems Lab
Eleven ideas that only matter once you have more than one machine.
Partitions
When the network splits the cluster.
A 5-node cluster just split into two groups that can't see each other. With a quorum rule, only the majority side keeps serving writes.
3/5 nodes
2/5 nodes
With a quorum rule, the minority side refuses writes the moment it can't reach a majority — safe, at the cost of availability on that side.