Upgrade Azure Stack HCI 22H2 to 23H2 on four node switchless cluster

Question

We have Azure Stack HCI 22H2 of four node cluster with switchless configuration that was supported for 22H2. I read that 23H2 only support up to three nodes for switchless. My question is why the spec is downgraded? Can we upgrade our 4 node cluster without buy new switches and reconfigure storage network before we upgrade?

Answer 1

Hi Robert Dellbrant,

Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.

The downgrade is possibly due to the increased network traffic and complexity of larger clusters, which can lead to performance issues and potential network outages. Therefore, Microsoft has limited the number of nodes supported for switchless configuration to three in order to ensure optimal performance and reliability.

Please refer the below documentation for Network considerations for cloud deployments of Azure Stack HCI, version 23H2 https://learn.microsoft.com/en-us/azure-stack/hci/plan/cloud-deployment-network-considerations

The following diagram summarizes storage connectivity options available to you for various deployments:

As described in the Azure Stack HCI system server requirements article, the maximum number of servers supported on Azure Stack HCI system is 16. You must have understanding of workload capacity planning, and number of server nodes required to run workloads on the infrastructure.

• If your workloads require four or more nodes: You can't deploy and use a switchless configuration for storage network traffic. You need to include a physical switch with support for Remote Direct Memory Access (RDMA) to handle storage traffic. For more information on Azure Stack HCI cluster network architecture, see Network reference patterns overview.
• If your workloads require three or less nodes: You can choose either switchless or switched configurations for storage connectivity.
• If you plan to scale out later to more than three nodes: You need to use a physical switch for storage network traffic. Any scale out operation for switchless deployments requires manual configuration of your network cabling between the nodes that Microsoft isn't actively validating as part of its software development cycle for Azure Stack HCI.

Here are the summarized considerations for the cluster size decision

The below doc shows the Features and improvements in Azure Stack HCI, version 23H2 https://learn.microsoft.com/en-us/azure-stack/hci/whats-new?tabs=2405releases The following document shows the Supported network topologies: https://learn.microsoft.com/en-us/azure-stack/hci/deploy/deployment-introduction

If you have any further queries, do let us know.

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