This section describes the host network configuration and network cards that are required to configure a basic stretched cluster. The purpose of this topology is to keep the host and inter-site configuration simple with little or no change to a standard stand-alone cluster networking architecture.
This topology uses two 25 GbE NICs for each host on both sites. One NIC is dedicated to intra-site storage traffic, similar to a stand-alone Storage Spaces Direct environment. The second NIC is used for management, compute, and Storage Replica traffic. To ensure management traffic is not bottlenecked due to high traffic on the Replica network, the customer network team should throttle traffic between the two sites using QoS rules. It is recommended that the network bandwidth is throttled to 50 percent of the capacity of the total number of network cards supporting the management NIC team.
This topology uses two 25 GbE NICs for each host to configure a high throughput stretched cluster and one rNDC for management traffic. One NIC is dedicated for intra-site RDMA traffic, similar to a stand-alone Storage Spaces Direct environment. The second NIC is used for replica traffic. SMB Multichannel is used to distribute traffic evenly across both replica adapters to increase network performance and availability. SMB Multichannel enables the use of multiple network connections simultaneously and facilitates the aggregation of network bandwidth and network fault tolerance when multiple paths are available. For more information, see Manage SMB Multichannel.
The Set-SRNetworkConstraint cmdlet is used to ensure that replica traffic flows only through the dedicated interfaces and not through the management interface. Run this cmdlet once for each volume.
PowerShell commands can be used to create affinity and anti-affinity rules for VMs in a cluster. An affinity rule is one that establishes a relationship between two or more resource groups or roles, such as VMs, to keep them together in an Azure Stack HCI cluster. An anti-affinity rule does the opposite, keeping specified resource groups apart from each other.
You can use storage affinity rules to keep a VM and its associated Virtual Hard Disk v2 (VHDX) on a Cluster Shared Volume (CSV) on the same cluster node. This ensures CSV redirection does not occur and keeps application performance at optimal levels. For more information, see Storage affinity rules.
For several proof-of-concept test scenarios, see the white paper Adding Flexibility to DR Plans with Stretch Clustering for Azure Stack HCI.
The Hybrid Cloud Management chapter covers how we can manage and monitor the hybrid cloud infrastructure from a single pane of glass.