Service Bus entity limit per message unit (MU)

Question

I need to migrate / upgrade my current Service Bus namespace, from standard tier to become premium tier. And I would to clarify the below:-

From the Azure document https://learn.microsoft.com/en-us/azure/service-bus-messaging/service-bus-migrate-standard-premium, its it mentioned that

• Migration supports 1,000 entities per messaging unit on the premium tier. To identify how many messaging units you need, start with the number of entities that you have on your current standard namespace.

And from another Azure document https://learn.microsoft.com/en-us/azure/service-bus-messaging/service-bus-quotas, it's mentioned that the below

Hence, please advice if the cap here apply to topics & queues only, but not applicable the subscription inside the topic? As in, assuming my current standard tier have 3 topics, and each topic contains 500 subscriptions. So now to upgrade it to premium tier, do I just need 1MU (as its considered as 3 entity only), or do I need 2MU (as the subscriptions are counted as well) ?

Thanks.

Answer 1

@John Wong Yek Hon Thanks for reaching out. Regarding your specific question about whether the cap applies to topics and queues only, or if it also includes subscriptions inside the topics:

The cap of 1,000 entities per messaging unit applies to all entities, including topics, queues, and subscriptions. Therefore, in your case, if you have 3 topics and each topic contains 500 subscriptions, you would have a total of 1,503 entities (3 topics + 1,500 subscriptions).

Given this, you would need 2 messaging units (MUs) to accommodate all your entities, as 1 MU can support up to 1,000 entities.

I hope this clarifies your query. If you have any further questions or need additional assistance, please let me know!