Cluster replica about Azure SQL MI with Business Critical

Question

Hi there,

I have some questions about Cluster replica for Azure SQL MI under Business Critical service tier.

1. Will replica server be create after I create an Azure SQL MI with Business Critical config?
2. If the answer of first question is yes, how can I connect to the replica server?
3. If the answer of first question is no, how to add second replica server into cluster?

Thanks

Answer 1

Hi
Li, Jindong •,

Welcome to Microsoft Q&A forum.

As I understand, you want to know about cluster replica of Azure SQL Managed Instance and its creation.

In the Business Critical model, compute and storage is integrated on each node. Replication of data between database engine processes on each node of a four-node cluster achieves high availability, with each node using locally attached SSD as data storage.

Every instance is a cluster of database engine nodes that contain copies of all the databases on an instance, with a primary database accessible for customer workloads, and three secondary databases containing copies of the data, ready for failover. The primary node constantly pushes changes to the secondary nodes in order to ensure the data is available on secondary replicas if the primary node fails for any reason.

Failover is handled by the SQL Server database engine – one secondary replica becomes the primary node and a new secondary replica is created to ensure there are enough nodes in the cluster. The workload is automatically redirected to the new primary node.

In case there's system failure, the database on primary instance is disabled and one of the secondary replicas immediately becomes the new read-write primary database, ready to process queries.

There is no manual intervention needed for secondary replica creation.

Please read this blogpost for High Availability in Azure SQL MI: Business Critical service tier:

https://techcommunity.microsoft.com/t5/azure-sql-blog/high-availability-in-azure-sql-mi-business-critical-service-tier/ba-p/3521212

Reference:

https://learn.microsoft.com/en-us/azure/azure-sql/managed-instance/service-tiers-managed-instance-vcore?view=azuresql&tabs=azure-portal

Let us know if this is helpful or you have further queries.

Thanks