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cre8toruk
Asked: 2020-10-23 04:41:17 +0800 CST

Highly available Azure VM

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I've deployed an Azure VM (woohoo!) and now I'm advised that it's really important that it keeps working. I've had a read up on Availability Zones and It looks like this might be the thing to do but I'm not sure if I understand it correctly.

If I have one VM in an availability zone, will that VM be replicated across the zones ?

thanks in advance,

Paul.

azure

2 Answers

  1. No

    Availability Zones are unique physical locations with independent power, network, and cooling. Each Availability Zone is comprised of one or more datacenters and houses infrastructure to support highly available, mission critical applications. Availability Zones are tolerant to datacenter failures through redundancy and logical isolation of services.

    Azure availability zones

    Virtual machines (VMs) are physically separated across zones, and a virtual network is created using load balancers at each site. These locations are close enough for high availability replication, so your applications stay running, despite any issues at the physical locations.

    Availability Zones help to spread VMs across different separated parts (with regards to availability) of a region to achieve high availability. But it is still necessary to use a load balancer and at least two VMs to achieve high availability. A single VM can not be high available as a single VM is not protected against hardware failure, misconfiguration, etc.

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  2. If you need high availability then you need to run at least 2 VM's. Running a single VM in an availability zone won't help you. Availability zones allow you to specify which zone in a region (usually there are 3 zones in a region) your VM goes into. To have HA you need to have at least 2 VM's so that they can sit in separate regions. You would then need to use something like a load balancer to direct traffic however you want.

    You can take this a step further and have 2 VM's, each in a separate region. Availability Zones split your VM's over different buildings, power, network etc. in the same region, but this won't protect your from large scale disasters that affect all zones.

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