Home > Storage > PowerFlex > White Papers > Dell APEX Block Storage for Azure: SQL Server 2022 Multi-Subnet Failover Clustering Deployment and Resiliency > SQL Server 2022 multi-subnet failover cluster on Dell APEX Block Storage for Azure
A multi-subnet failover cluster is a highly available solution that enables SQL Server 2022 instances to failover over various subnets. This functionality provides improved availability and disaster recovery capabilities for SQL Server deployments and is especially relevant when the APEX Block Storage cluster is configured across multiple-AZs, each one with its own subnet.
In a multi-subnet failover cluster, the SQL Server instances with APEX Block Storage multi-AZ configuration, can be set to automatically fail over in case one of the AZs has an outage.
While a simpler configuration of SQL Server can be deployed with APEX Block Storage, such as when using a single AZ instead of multiple or when SQL Server is configured as a non-clustered, this paper explains and demonstrates SQL Server 2022 multi-subnet cluster on Azure cloud with APEX Block Storage as a reference architecture for a highly available solution.
An APEX Block Storage deployment in Azure is set as a two-layer design, in which compute, and storage instances are distinct. The two-layer design enables Azure VM instances that are compute oriented for databases and application workloads to be configured and scale separately from Azure VM instances that are optimized for storage, providing customers with more flexibility.