Calculate required Application gateway instance count

Senthilnath T M 26 Reputation points
2021-09-21T05:36:31.703+00:00

We have an Azure Application gateway (WAF v1, Large). Metrics show the CPU utilization is less than 15%.

  1. Does this mean the App GW utilization is less?
  2. Based on this can i reduce the instance count?

Let me know if other factors/metrics needs to be considered.

Azure Application Gateway
Azure Application Gateway
An Azure service that provides a platform-managed, scalable, and highly available application delivery controller as a service.
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  1. GitaraniSharma-MSFT 48,531 Reputation points Microsoft Employee
    2021-09-21T13:20:11.71+00:00

    Hello @Senthilnath T M ,

    Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

    1) Application gateway v1 CPU Utilization displays the utilization of the CPUs allocated to the Application Gateway. CPU usage should not regularly exceed 90%. You can indirectly control or improve CPU utilization by modifying the configuration of the Application Gateway by increasing the instance count or by moving to a larger SKU size, or doing both and vice-versa.
    Refer : https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-metrics#metrics-supported-by-application-gateway-v1-sku

    In your case, if the Metrics show the CPU utilization is less than 15%, then yes, this mean the Application utilization is less.

    2) Yes, you can reduce the instance count if your Application utilization is less than 15%.

    Points to be considered:

    In case you are interested to migrate your Application gateway from v1 SKU to v2 SKU, you can refer the below article:
    https://learn.microsoft.com/en-us/azure/application-gateway/migrate-v1-v2

    Kindly let us know if the above helps or you need further assistance on this issue.


    Please "Accept the answer" if the information helped you. This will help us and others in the community as well.


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