Merge pull request #180543 from sethmanheim/az1

Add availability zones article

Author: johne2021

articles/notification-hubs/TOC.yml

@@ -89,7 +89,9 @@
   - name: UWP React Native sample overview
     href: uwp-react.md
 - name: Concepts
-  items: 
+  items:
+  - name: Availability zones
+    href: availability-zones.md
   - name: Transport Layer Security (TLS)
     href: notification-hubs-tls12.md
   - name: Enterprise push architecture guidance

articles/notification-hubs/availability-zones.md

@@ -0,0 +1,30 @@
+---
+title: Availability zones in Azure Notification Hubs
+description: Learn about availability zones and high availability with Azure Notification Hubs. 
+author: sethmanheim
+ms.author: sethm
+ms.service: notification-hubs
+ms.topic: conceptual
+ms.date: 11/19/2021
+ms.custom: template-concept
+---
+
+# Availability zones
+
+Azure Notification Hubs now supports [availability zones](/azure/availability-zones/az-overview), providing fault-isolated locations within the same Azure region. To ensure resiliency, three separate availability zones are present in all availability zone-enabled regions. When you use availability zones, both data and metadata are replicated across data centers in the availability zone.
+
+## Feature availability
+
+Availability zones support will be included as part of an upcoming Azure Notification Hubs Premium SKU. It will only be available in [Azure regions](/azure/availability-zones/az-region) where availability zones are present.
+
+> [!NOTE]
+> Until Azure Notification Hubs Premium is released, availability zones is by invitation only. If you are interested in using this feature, contact your customer success manager at Microsoft, or create an Azure support ticket which will be triaged by the support team.
+
+## Enable availability zones
+
+At this time, you can only enable availability zones on new namespaces. Notification Hubs does not support migration of existing namespaces. You cannot disable zone redundancy after enabling it on your namespace.
+
+## Next steps
+
+- [Azure availability zones](/azure/availability-zones/az-overview)
+- [Azure services that support availability zones](/azure/availability-zones/az-region)