A node can disappear or be destroyed at any time without notice. In order to preserve the integrity of the overall persisted data, each partition is backed up on a number of nodes other than the owner. An individual node can only hold each partition once (either owning or backing it up). Should a node die, the ownership of any partitions that were owned by the now defunct node will be migrated to one of the backups so that no data loss is experienced.

Following the node's loss, Hazelcast will start to replicate the migrated partitions over to another node in the background to cater to the fact that there are fewer backups available now than what were configured earlier. This will restore back the former resilience that was configured before. The number of backups that Hazelcast will create is configurable, depending on your hardware's stability, appetite for risk, and the available memory.

We can configure the number of backups that should be kept—either globally...