Scaling partitions for the premium messaging tier of Azure Service Bus is now in public preview. Meaning that throughput is no longer limited by the performance of a single message broker. Furthermore, a temporary outage of a message broker doesn’t make a partitioned queue or topic unavailable, as messages will be retried on a different partition.
Partitions must be set up in the creation of a new namespace and are available to be scaled up to a maximum of four partitions. Currently, this feature is not available in UK South, but we’re sure we will see it rolling out shortly.
For more information, including current limitations, please see the documentation: Enable partitioning in Azure Service Bus Premium namespaces.