Azure SQL Server Always on AG with multi-sibnets

Question

We are planning to set-up always on AG in azure which SQL server 2016 on WS2016. As perdocumentation, we want to avoid load balancer and go with multi-subnet. The question here is, does the 2 azure VM's/nodes must be in different zones in a region ? We want to have both the VM's in same zone under same virtual network but different subnets. Does this configuation work ?

Answer 1

You don't have to use different Availability Zones, but if you are not then you should use an Availability Set to ensure that the SQL VMs are not placed on the same Update or Fault Domains. It is documented in https://learn.microsoft.com/en-us/azure/azure-sql/virtual-machines/windows/availability-group-manually-configure-prerequisites-tutorial-multi-subnet?view=azuresql#create-sql-server-vms:

Availability - Availability Zones For the highest level of redundancy, resiliency and availability deploy the VMs within separate Availability Zones. Availability Zones are unique physical locations within an Azure region. Each zone is made up of one or more datacenters with independent power, cooling, and networking. For Azure regions that do not support Availability Zones yet, use Availability Sets instead. Place all the VMs within the same Availability Set.