Clustering for Azure SQL Database

Clustering provides high‑availability and load‑balancing for Azure SQL Managed Instances and the premium tier of Azure SQL Database. This guide walks you through the concepts, setup, monitoring, and best practices.

When to Use Clustering

Clustering is ideal for workloads requiring:

• Zero‑downtime maintenance.
• Automatic failover across regions.
• Scalable read‑only replicas.

Creating a Cluster

Use the Azure portal or Azure CLI. Below is a CLI example:

az sql mi create \\
    --name MyCluster \\
    --resource-group MyRG \\
    --location eastus \\
    --sku GP_Gen5_8 \\
    --subnet /subscriptions/xxxx/resourceGroups/MyRG/providers/Microsoft.Network/virtualNetworks/MyVnet/subnets/default
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Monitoring Cluster Health

SELECT replica_id, replica_server_name, role_desc, state_desc 
FROM sys.dm_hadr_availability_replica_states 
WHERE is_local = 1;
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Best Practices

• Deploy clusters in multiple Availability Zones.
• Use read‑scale replicas for reporting workloads.
• Regularly test failover procedures.

Frequently Asked Questions