Fail to deploy 3rd VM in VMSS

Question

Hello!

I have a VMSS with auto-scale policy to deploy new VM when average CPU is over 80% for 5 minutes

Initial and Minimum instance count is 1 maximum is 3

It deploys second machine with no issues but no matter how many times I tried it gives an error when trying to deploy 3rd one. Attaching error below

Error code: ResourceOperationFailure

Message: The resource operation completed with terminal provisioning state 'Failed'.

Also on the ALL VMSS screen I see information that this VMSS has 3 instances but when going into INSTANCES tab I only see two

Answer 1

Hello Mateusz Domański,

Welcome to microsoft Q&A, thankyou for posting your query here.

Check if there is sufficient IP address space available in the subnet associated with your VMSS.If the subnet is running out of available IP addresses, the third VM would not be able to provision correctly.

Check if the configuration of your VMSS regarding fault domains and update domains could be affecting the provisioning.

Verify that the health probes are responding correctly. If a probe fails consistently, it might prevent scale-out operations.

Hope this helps you.