Is creating a single VM in a one Availability Zone the same as specifying "No Infrastructure Redundancy"?

Question

Hi,

I am trying to get my head around whether it is best to always specify a specific numbered AZ for a single instance VM (that has not other dependencies), or whether it is better to specify "No Infrastructure Redundancy"?

It seems to me that specifying "No Infrastructure Redundancy" - means that the VM can land in any one of the three AZ zones in the Region (based on the Azure algorithm), which is pretty much the same as chosing a single AZ zone yourself..

I guess that the Azure Algorithm will ensure that the managed disk and public IP etc will all land in the same AZ as the VM itself if you specify "No Infrastructure redundancy" (because why wouldn't it as there would be a performance hit if it did not) - is this correct?

So, specifying a single AZ only has the benefit that you actually know which AZ the VM and its resources are in, rather than letting the Azure Algorithm decde - is this correct?

Or am I missing something here?

Thanks

Gary

Answer 1

Choosing a Single Availability Zone: You know exactly which physical area (zone) in Azure your VM is in. This is good for specific needs like compliance or performance.

No Infrastructure Redundancy: Azure decides where to put your VM, possibly in any of the available zones in a region. This is like saying, "I'm fine with any zone, you choose, Azure."

In essence, if you need to know exactly where your VM is for specific requirements, pick a zone. If you're okay with Azure deciding and possibly saving some costs, go with "No Infrastructure Redundancy."

Answer 2

Hi @Gary Mansell ,

your guesses and assumptions are right.

If you choose No Infrastructure Redundancy Azure algorithm will pick an Azure Availability Zone for you.

If you choose an Azure Availability Zone for a single VM you decide if the VM will be deployed in Zone 1, 2 or 3, depending which zone you select.

But be aware: The mapping of the zones (number 1- to 3) is specific for each Azure Subscription. This means for Subscription1 the 3 zones are mapped maybe to different numbers compared with Subscription2.

---

(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)

Regards

Andreas Baumgarten