Spot VMs for cost savings in Azure - Step-by-Step Execution

Process Flow - Spot VMs for cost savings

Request Spot VM

↓

Azure checks capacity

↓

Capacity available?

No→Spot VM denied

↓

Spot VM allocated

↓

Run workload

↓

Preemption event?

Yes→VM evicted

↓

Workload stops

↓

Workload completes

↓

End

The flow shows requesting a Spot VM, Azure checking capacity, allocating if available, running workload, and possible eviction if capacity is needed.

Execution Sample

Azure

az vm create --name mySpotVM --resource-group myRG --image UbuntuLTS --priority Spot --max-price -1

This command creates a Spot VM in Azure with no max price limit, allowing cost savings but possible eviction.

Process Table

Step	Action	Azure Response	VM State	Notes
1	Request Spot VM creation	Check capacity	Pending	Azure checks if Spot capacity is available
2	Capacity available?	Yes	Allocated	Spot VM is allocated and starts running
3	Run workload	Running	Running	Workload runs on Spot VM
4	Preemption event occurs	Eviction notice	Evicted	Azure needs capacity, evicts Spot VM
5	Workload stops	VM deallocated	Stopped	Spot VM is stopped, workload interrupted
6	Request Spot VM creation	Check capacity	Pending	If retried, process repeats
7	Capacity available?	No	Denied	Spot VM creation denied due to no capacity

💡 Execution stops when Spot VM is evicted or creation is denied due to capacity.

Status Tracker

Variable	Start	After Step 2	After Step 4	After Step 5	After Step 7
VM State	None	Allocated	Evicted	Stopped	Denied
Azure Capacity	Unknown	Available	Needed Elsewhere	Needed Elsewhere	Unavailable

Key Moments - 3 Insights

Why can a Spot VM be evicted even if my workload is running?

Because Azure can reclaim Spot VMs anytime when it needs capacity, as shown in execution_table step 4 where a preemption event causes eviction.

What happens if there is no capacity available when requesting a Spot VM?

The Spot VM creation is denied immediately, as shown in execution_table step 7 where capacity is unavailable and VM state is Denied.

Does setting max-price to -1 guarantee my Spot VM will never be evicted?

No, max-price -1 means you accept any price, but eviction depends on Azure capacity needs, not price, as seen in the eviction event in step 4.

Visual Quiz - 3 Questions

Look at the execution_table, what is the VM State after Azure confirms capacity is available?

A Allocated

B Pending

C Evicted

D Denied

💡 Hint

Check execution_table row 2 under VM State column.

At which step does the Spot VM get evicted due to capacity needs?

A Step 3

B Step 4

C Step 6

D Step 7

💡 Hint

Look for 'Preemption event occurs' in execution_table.

If Azure capacity is not available, what is the VM State shown in variable_tracker after that step?

A Allocated

B Running

C Denied

D Stopped

💡 Hint

See variable_tracker column 'After Step 7' for VM State.

Concept Snapshot

Spot VMs are low-cost Azure VMs that can be evicted anytime.
Request Spot VM with priority Spot and optional max-price.
Azure allocates if capacity is free; otherwise denies.
Workloads run until eviction (preemption) occurs.
Best for interruptible, flexible workloads to save cost.

Full Transcript

Spot VMs in Azure are special virtual machines offered at a lower price because Azure can reclaim them anytime when it needs capacity. When you request a Spot VM, Azure checks if there is enough capacity. If yes, it allocates the VM and your workload runs. However, if Azure needs the capacity back, it sends an eviction notice and stops the VM, interrupting your workload. If there is no capacity at request time, the Spot VM creation is denied immediately. Setting max-price to -1 means you accept any price, but eviction depends on capacity, not price. Spot VMs are best for workloads that can handle interruptions and want to save money.