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AKS Cluster Re-Deployment in a Single Zone

Bramandlapally, Mahesh 60 Reputation points
2025-08-11T02:35:49.3266667+00:00

Hi Team,

Requirement: Addition of new GPU Node pool in the existing AKS cluster.

We need guidance on the following scenario related to our AKS deployment:

 1. We need to deploy a new node pool using the SKU NCads_H100, but according to Microsoft Premium capacity team, this SKU is currently available only in Zones 1 and 3 within the US East region.

  1. Our existing AKS cluster is configured across all three zones (Z1, Z2, and Z3), and the currently active node pool - node is deployed in Zone 2, where the required SKU is not available.

Given this constraint, our application team has suggested reconfiguring the cluster to operate in a single zone (either Zone 1 or Zone 3), where the required SKU is available.

We would appreciate your guidance on the best approach to proceed:

  • Should we consider redeploying the cluster in a single zone to accommodate the SKU? (But definitely the existing configuration on existing Node (which is Z2) will be deleting the configuration)
  • Are there any recommended practices or risks associated with moving from a multi-zone to a single-zone setup?
  • Would it be feasible to isolate the new node pool in a supported zone while keeping the rest of the cluster multi-zonal?

Thank you for your support and looking forward to your advice.

Azure Kubernetes Service
Azure Kubernetes Service
An Azure service that provides serverless Kubernetes, an integrated continuous integration and continuous delivery experience, and enterprise-grade security and governance.
Accepted answer
  1. Anusree Nashetty 5,735 Reputation points Microsoft External Staff Moderator
    2025-08-11T05:39:40.76+00:00

    Hi Bramandlapally, Mahesh,It is feasible to add a new node pool specifically aligned to Zones 1 or 3, while keeping your cluster multi-zonal. AKS supports zone-aligned node pools, meaning you can have one node pool dedicated to a specific zone (like Z1 or Z3), while other node pools remain multi-zonal or aligned to other zones.

    Zone-aligned Node Pools: Each node pool can be pinned to a specific zone during creation. This ensures only the new GPU node pool is in the supported zone, but the rest of the cluster retains its existing configuration. https://learn.microsoft.com/en-us/azure/aks/reliability-availability-zones-configure

    Moving your entire cluster to a single zone is generally not recommended unless all workloads can tolerate reduced high availability.

    • Loss of Resilience: Operating in a single zone reduces resiliency. Any outage in that zone will impact your entire cluster.
    • High Availability: AKS best practices strongly recommend using multi-zone clusters for mission-critical applications, as zone failure will only impact part of the cluster. If you reconfigure everything to a single zone, a zone-level outage will bring down all workloads.
    • Redeploying System Node Pool: If you switch the system node pool (and thus the control plane) to a single zone, this would require re-creating the cluster or significant downtime for migration. Existing resources and state in Zone 2 may be lost unless explicitly backed up and restored.

    If you have any further queries, let me know.

    You found this answer helpful.

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