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Azure / Azure-Proactive-Resiliency-Library-v2

Azure Proactive Resiliency Library v2 (APRL) - Source for Azure WAF reliability guidance and associated ARG queries
https://azure.github.io/Azure-Proactive-Resiliency-Library-v2/
MIT License
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❓👂 Question/Feedback - Availability set retirement #235

Open igorjnzl opened 1 week ago

igorjnzl commented 1 week ago

Question/Feedback

Looking at recommendation Migrate VMs using availability sets to VMSS Flex, it states that availability sets will soon be retired, are you able to link the retirement notice / announcement?

https://azure.github.io/Azure-Proactive-Resiliency-Library-v2/azure-resources/Compute/virtualMachines/#migrate-vms-using-availability-sets-to-vmss-flex

FallenHoot commented 4 days ago

The understanding is that Availability sets have no date for deprecation. Microsoft usually announces this 12 months before, but it is set to be deprecated. Knowing this, it would be up to the judgment on if you should use them or not. Is it more work changing this in the future compared to changing it now. Does VMSS Flex offer the same benefits of AvSets?

I agree the wording needs to be changed to reflect this. Have created a PR to reflect this.

ejhenry commented 4 days ago

@igorjnzl thanks for opening the issue. This recommendation has been verified by the PG and they have been unambiguous with stating customers should not continue to use AvSets.

@FallenHoot before merging your PR we'll need to check with the DRI and PG that they concur with the change.

cc @michielvanschaik @hannah-leland

tksh164 commented 2 days ago

I also curious that recommendationImpact: High. It is the highest impact level. Is this so critical at this time?

In my understanding, that retirement has not yet documented. It is just a recommendation currently. So, this APRL recommendation will surprise customers.

https://learn.microsoft.com/en-us/azure/virtual-machines/availability-set-overview

We recommend that customers choose virtual machine scale sets with flexible orchestration mode for high availability with the widest range of features. Virtual machine scale sets allow VM instances to be centrally managed, configured, and updated, and will automatically increase or decrease the number of VM instances in response to demand or a defined schedule. Availability sets only offer high availability.

ejhenry commented 2 days ago

Perhaps we just remove the reference to retirement from the recommendation until the announcement happens? It seems to be taking away from the key component of the recommendation that AvSets do not support zonally deployed VMs. Thoughts?

Regarding impact level, moving off AvSets is critical for customers to achieve zone redundancy so I don't think we want to lower the impact.

tksh164 commented 1 day ago

Thank you @ejhenry. It makes sense to me. So, the recommendation was not intended to the AvSets retirement, it was intended to the AvSets to AZ migration.

If so, I suggest changing the description/title of the recommendation to a more focusing one to the AvSet to AZ migration like "Migrate VMs using availability sets to availability zones". Because customers have two options, not only VMSS Flex. The best option depends on the workload, I think.

For example, an AvSet has two ADDS DC VMs. In this case we could not scale out only increase instance count. Is VMSS Flex the best option even in this case?

Also, "use VMSS Flex" is not equal to "use AZ" because VMSS Flex supports regional (non-zonal) deployments. I believe.

And more 2 points on the recommendation:

  1. longDescription: VMSS Flex has update domains? It seems no update domains.

  2. learnMoreLink: I suggest adding the following link.