Expected backup duration

In version 4.2 HiveMQ introduce a new Backup and Restore functionality. It is useful for moving state from one HiveMQ cluster to another as well as restoring previous state in a current deployment.

Being able to estimate the duration of backup creation in advance can be useful to administrators.

The key factors determining the duration are queue size as well as the cluster’s node count.
Both will scale almost linearly. This means doubling the messages held in the queue will
extend the duration of the backup almost by the factor of 2, while adding a second node to the
cluster will almost exactly halve the duration.

In our tests single nodes required about 1 hour to transfer state with 1.5 million queued messages (each ~0,5kb payload) and 300k sessions.