Azure Bandwith - Data Transfer Out

Question

I have created 2 CentOS VMs in my Azure. Nothing fancy, 2 CPUs, 2 GB RAM and 10GB SSD - both cost pennies to run, both in the same resource group in Europe West, etc. What have me shocked are 2 spikes of "Bandwith - Data Transfer Out". One day I got charged 17$ for one VM and another day 14$ for another VM. How come? it's just not possible to be charged like that...

Anyone had similiar issue?

Thx for suggestions.

Answer 1

Hello, @Piotr Wlodarek !

Edit: Updated with new recommendations and a correction regarding billing after additional investigation.

What are these outbound network charges on my virtual machine?
First and foremost, determining exactly what the nature of your VM traffic is will depend on agent logs, system logs, monitoring events, and specific network tools. I've included a list of network monitoring tools and solutions below.

As far as an educated guess is concerned, that looks to be several hundred GB worth of outbound data. This could be caused by creating a replica in another region as that would be considered outbound bandwidth and seems to match the amount of data in question. More information can be found on the Azure bandwidth pricing page:

https://azure.microsoft.com/en-us/pricing/details/bandwidth

Talking to Billing is another option and I should note that billing support is available to all Azure customers. You can open a billing support request in the Azure Portal by going to Help + support > New support request > Billing and then complete the wizard.

Looking up costs using the Azure Pricing Calculator
Looking at the Azure Pricing Calculator today and running some test numbers, sending data from West Europe to North Europe was about 2.5x the cost of sending data from West Europe to West US (Inter Region, Internet Egress was about 35% more). Using the last example of sending data to West US, it would take about 300GB-350GB in traffic to see those charges.

Monitoring VM network traffic
There are a large number of options available to you when it comes to monitoring network traffic traffic on your VM. Azure Monitor and Log Analytics are very useful here and I'm including a link to an Azure blog with a brief walkthrough as well as some common queries. Network Watcher and Traffic Analytics are also a good resources:

• Azure Blog: Analysis of network connection data with Azure Monitor for virtual machines
• Microsoft Learn: Log network traffic to and from a virtual machine using the Azure portal (Network Watcher)
• Microsoft Learn: Traffic Analytics

If you still need help, let me know and we can do some additional troubleshooting.