Unable to add new VM to LoadBalancer

ExtraEgg 30 Reputation points
2023-06-02T12:24:04.4566667+00:00

Hiya,

We have a Basic SKU LB with a single front end IP and single backend-pool that has a single Windows server VM in a Vnet + NSG.

The Windows VM has no availability zone <- I think this is what's is killing me

All been running fine for half a year or so.

I want to create a new Linux VM in the same Vnet and add it to the loadbalancer.

So I created a new backend-pool.

Create the new VM with no availability and select no public IP and to add it the Vnet and new backend-pool.

I have tried many different combinations, like creating VM then trying to add to new pool, or trying to add to old pool.

Always same error:

some-vm-1 is using different Availability Set than other Virtual Machines connected to the Load Balancer(s) LoadBalancerA.

One option seems to be to delete the existing VM and recreate with an availability set, but this will be a big disruption and will it even work?

We use the loadblancer as part of firewall solution (with NSG) and to be able to access resources within the Vnet from public internet. Nothing fancy.

What am I doing wrong?

Azure Virtual Machines
Azure Virtual Machines
An Azure service that is used to provision Windows and Linux virtual machines.
7,532 questions
Azure Load Balancer
Azure Load Balancer
An Azure service that delivers high availability and network performance to applications.
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Accepted answer
  1. TP 83,311 Reputation points
    2023-06-02T12:36:01.1966667+00:00

    HI,

    Basic SKU Load Balancer restricts you to having backend with single VM, or VMs in same availability set, or VMs in VM Scale Set. So from your description you have an existing backend with single VM not in an availability set, so you can't add a new one to the backend.

    One option would be to re-create things so you have two VMs in same availability set for your backend pool.

    Azure Load Balancer SKUs - SKU comparison

    https://learn.microsoft.com/en-us/azure/load-balancer/skus#skus

    Please click Accept Answer if the above was helpful. If you have a question please add a comment.

    Thanks.

    -TP


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