Do VMs in Azure Availability Set automatically replace the one which goes down?

Hi @newhdanalyst

Azure Availability Sets are designed to ensure high availability for your VMs by distributing them across multiple fault domains and update domains. However, they do not automatically replace a VM that goes down. Instead, they help minimize the impact of hardware failures, network outages, or maintenance events.

In your case:

• VM1: If you don’t see any fault domain or update domain, it might not be correctly configured within the availability set.
• VM2: Being in fault domain 1 and updating domain 1 means it’s correctly placed within the availability set.

If VM1 goes down, VM2 will not automatically start receiving user connection requests unless you have a load balancer configured to distribute traffic between the VMs. When VM1 comes back up, it will resume its role, but again, traffic distribution depends on your load balancer configuration.

Consider setting up an Azure Load Balancer in front of your VMs to ensure seamless failover and load distribution. This way, if one VM goes down, the load balancer can redirect traffic to the remaining healthy VMs.

Reference:
https://video2.skills-academy.com/en-us/azure/virtual-machines/availability-set-overview

https://video2.skills-academy.com/en-us/azure/virtual-machine-scale-sets/flexible-virtual-machine-scale-sets-migration-resources

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