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richardwolford-7948 asked AndreasBaumgarten commented

Availability zones for Virtual Machines

I'm a bit confused after reading a LOT of Microsoft documentation on VMs and Availability Zones. If I create a VM in East US 2 and place it in an availability zone, and that zone goes down, is my VM inaccessible? I can't seem to get a clear answer on this.

Thanks ahead of time

azure-virtual-machines
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AndreasBaumgarten answered AndreasBaumgarten commented

Hi @richardwolford-7948 ,

based on the scenario you described above the the "single" VM will be unavailable if the zone goes down.
Availability zones don't work with single VMs. But if an IT service is running on more than one VM the Availability Zones could make sense.

For example: AD Domain Controllers
If you create 2 Domain Controller VMs it makes sense to create the 2 VMs in different Availability Zones (e.g. DC1 in Zone 1 and DC2 in Zone 2).
if both zones are up -> Everything is working fine, bot VMs are up and running and doing their job -> AD service is up
Zone 1 goes down -> DC1 is unavailable, DC2 is up and running and is doing the job -> AD service is up
Zone 2 goes down -> DC2 is unavailable, DC1 is up and running and is doing the job -> AD service is up
Zone 1 and Zone 2 goes down -> DC1 is unavailable, DC2 is unavailable -> AD service is down

Another example could be web server (with zone redundant Load Balancer) ... or SQL Server clusters.


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

Regards
Andreas Baumgarten


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Thank you very much, this is what I thought the case was but I wanted to make sure my understanding was correct, Azure changes so often I thought I had missed something.

Thanks again!

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Hi @richardwolford-7948 ,

you are welcome. And thanks for the feedback!


Kind regards
Andreas Baumgarten

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