Why ADX uses 2 VMs SKUs D11 v2 and D2a v4 ?

Question

Hello Team,

Analysing my costs, I noticed that there are 2 SKUs associated with ADX, D11 v2 and D2a v4.

The purpose of D11 v2 is clear - this is the one I selected as underlaying machine for the cluster and has utilization 100% since my cluster is always on.

But where is D2a v4 coming from?

This one is not even always on but it has nothing to do with what I consider normal uptime of ADX and seem to be a system VM - this one was down 6 days this month but for sure I didn't have 6 days of downtime.

Answer 1

I think I got the answer already ( thanks to AI Search functionality of this forum ).

D2a v4 is the data management instance which is automatically created to manage the underlying compute and storage data and it is sized automatically based on the size of the engine instance D11 v2 which is selected by users.

MS Docs reference: https://learn.microsoft.com/en-us/azure/data-explorer/pricing-calculator?WT.mc_id=AZ-MVP-5002324#data-management-instances
Questions with related answer and interesting cost analysis: https://learn.microsoft.com/en-us/answers/questions/1650692/azure-data-explorer-effective-costs-different-than

Answer 2

Hi @FedericoZarelli-6386

I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others "I'll repost your solution in case you'd like to accept the answer.

Issue: Analysing my costs, I noticed that there are 2 SKUs associated with ADX, D11 v2 and D2a v4.The purpose of D11 v2 is clear - this is the one I selected as underlaying machine for the cluster and has utilization 100% since my cluster is always on.

But where is D2a v4 coming from?

This one is not even always on but it has nothing to do with what I consider normal uptime of ADX and seem to be a system VM - this one was down 6 days this month but for sure I didn't have 6 days of downtime.

Solution: After reviewing the information, found that D2a v4 is a Data Management Instance in Azure Data Explorer (ADX). This instance is automatically created to handle compute and storage management tasks. Its size is dynamically determined based on the selected engine instance (D11 v2).

For more details, you can refer to the Microsoft Docs: Data Management Instances in ADX

Additionally, here’s a related discussion with insights on ADX costs: Azure Data Explorer Effective Costs

If I missed anything please let me know and I'd be happy to add it to my answer, or feel free to comment below with any additional information.

If you have any other questions, please let me know. Thank you again for your time and patience throughout this issue.

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