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I currently have a website in IIS in Azure VMs. I have the site replicated over 2 VMs in 2 availability zones.

This protects the site against downtime.

I need to implement some scalabilty for high load moments. This seems to be what Scale sets were created for.

1) How can i combine scalability and redundancy?

So when under load the VM scales but when a vm goes down i maintain service?

2) With Scale sets how do i deploy site updates?

Do I need to create a new VM VHD image every time i need to update the site and then re-image to it?

The whole management of VHD images seems rather difficult.

Alex Stephens
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1 Answers1

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A1: For the VMSS, it's similar to the availability set. So itself means the redundancy. The description below:

A virtual machine scale set allows you to deploy and manage a set of identical, auto-scaling virtual machines. VMs in a scale set are distributed across logic fault and update domains in one or more placement groups. These are groups of similarly configured VMs, similar to availability sets.

A2: There are ways to update the application in the VMSS, one is that update the VMSS with a new custom image and another is that use the extensions. I suggest if you just for the test and develop purpose, you can just use the extension to update the application. When the application is OK, you can create a total image.

Charles Xu
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  • Thanks Charles. So, i would update another VM and test. When happy i can create an image from it and update the scale set image to use it? – Alex Stephens May 20 '19 at 05:59
  • @AlexStephens Yes, I suggest so. It's a little more complex if you always update with the new image. – Charles Xu May 20 '19 at 06:03
  • They use the same 'availability' term, but availability sets are not the same as availability zones. You can configure your VMSS to use availability zones though: https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-use-availability-zones – Nathan Kuchta May 20 '19 at 18:13
  • Building a VHD has also been made a bit easier with Azure Image Builder: https://cloudblogs.microsoft.com/opensource/2019/05/07/announcing-the-public-preview-of-azure-image-builder/ – Nathan Kuchta May 20 '19 at 18:18