Introduction
What are Event Hubs?
Azure Event Hub is a big data streaming platform and event ingestion service by Microsoft Azure. It’s designed to ingest, buffer, store, and process millions of events per second in real time.
Feature Comparison
The Standard tier of Azure Event Hubs provides features beyond what is available in the Basic tier. The following features are included with Standard:
|
Feature |
Basic Tier |
Standard Tier |
|
Capture Feature |
❌ Not available |
✅ Available |
|
Virtual Network Integration |
❌ Not available |
✅ Available |
|
Auto-Inflate |
❌ Not available |
✅ Available |
|
Consumer Groups |
Limited (only 1 group) |
Up to 20 consumer groups |
|
Message Retention |
Up to 1 day |
Up to 7 days |
Many organizations or users choose to downgrade their Event Hubs from the Standard to the Basic tier to reduce costs or for other reasons.
However, it's important not to overlook that certain features available in the Standard tier are not supported in the Basic tier. These differences mentioned above should be carefully reviewed before making the switch.
So, while you try to switch from the Portal, you will be able to see that Basic tier is enabled, and you are good to migrate from Standard to Basic
However, when you start migrating from the Portal you will see the error below which means your Event Hub capture feature is enabled and you need to disable it first before migrating.
Failed updating Event Hubs namespace with error: Code: 'MessagingGatewayConflict' with Message: 'Namespace tier cannot be downgraded, as Archive is not available in Basic tier. TrackingId:xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxx-xxxxxx-xxxxxxxxxx-xxxxxxxexx_xxx, SystemTracker:eventhubnamespacename.servicebus.windows.net:$tenants/eventhubnamespacename.
When running a script for multiple namespaces, this error may not appear. You might incorrectly assume the migration succeeded, while the status will remain 'Not Active.' This can silently break functionality.
Current Limitation
- If Capture Feature is enabled, it should not allow to migrate on the first place.
- You must have created multiple Consumer groups for Standard tier. However, after migration, you can use only 1 Consumer Group that is $default for the basic tier.
- If Auto-inflate is enabled, it will ask you to disable first and then start the migration.
In Ideal scenario, you should not be able to pull events from other consumer groups as Basic only offers 1 consumer group per entity for Basic.
However, if you try to pull events from other consumer groups it does not throw any throw Runtime Error.
This bug has been identified by our Internal Product Group team, and they are working on it to fix this bug and release it sooner.
Before implementing this workaround addressed below described in this article, I recommend checking the status of this feature request. Event Hubs is continuously evolving, and by the time you're reading this, the limitation might have been addressed in the upcoming weeks.
Workaround
- You need to disable Capture feature first and check the Status = Active. Then start the migration process and check again the Status = Active.
- Delete all the other Consumer Groups which you created in Standard tier to avoid confusion.
- Do not use any other Consumer groups other than $default in your receiver applications while pulling the Events from the Event Hub.
Conclusion
"Thanks for reading! I hope this article helps clarify the nuances of migrating from the Standard to Basic tier in Azure Event Hubs. As the platform evolves, keep an eye on official documentation and Azure updates. This limitation may be resolved soon, making migration more seamless in the future."
Microsoft