Azure VMSS with Spot

Question

Use Spot VMSS and set maxPrice = -1

"priority": "Spot",
"evictionPolicy": "Deallocate",
"billingProfile": {
"maxPrice": -1
}

But i do not know why the vmss instance auto stopped by MS even I set the max price to -1.

Answer 1

Hello @添翼 韩 ,
Welcome to Microsoft QnA.
I understand your query and here's why the eviction happened.

Azure Spot VM and scale sets do not have an SLA once created, which means that they can be terminated at any moment with up to 30 seconds of notice. Whenever Azure needs the capacity back, the Azure infrastructure will send your compute instance an eviction notice and proceed to evict that same instance based on your configured eviction policy.

Eviction depends on two factors : price and capacity. While you have set the price to -1 (which means the VM won't be evicted for pricing reasons. The max price will be the current price, up to the price for standard VMs), however, the eviction happened because Azure wanted the capacity back for that VM, hence the Azure infrastructure evicted the sport VM that you were running in that particular region due to capacity demand.

Please understand that Spot VMs are not recommended for critical workloads, they should only be used for workloads that can handle interruptions like delayable batch or queue processing jobs, non-critical dev/test environments, and large, delayable compute workloads.
For further details, please refer : https://learn.microsoft.com/en-us/azure/architecture/guide/spot/spot-eviction

I hope this helps. Please feel free to reach back and tag me in your response if you have further queries.

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