Cluster sets are a cloud scale-out technology that provides the benefit of combining multiple clusters without sacrificing resiliency. It encapsulates a cluster within a cluster-set by loosely coupling a group of multiple clusters. The great thing about cluster sets is that a virtual machine (VM) can seamlessly live migrate from one cluster to a host in a different cluster and continue to access its storage.
As mentioned in earlier chapters, we do not recommend expanding a 2-node cluster or expanding a cluster built on switchless networking topology. However, with cluster sets we can get around that limitation. Cluster sets can also be valuable for addressing the homogeneity requirements of HCI clusters. For example, if an Azure Stack HCI cluster is deployed on 14G hardware and we now want to use 15G hardware for expansion, we can do that with the help of cluster sets.
Note: From a performance perspective, it is important to note that if you want to take advantage of another cluster in a cluster set, it is best to perform not only a Live Migration of VMs but also a Storage Migration so that VM compute and storage reside on the same cluster.
Benefits of cluster sets:
- Combine multiple smaller clusters into single namespace without sacrificing resiliency.
- Manage Failover Cluster life cycle without impacting running VMs.
- Benefit from Azure-like Fault Domains and Availability Sets across clusters.
- Scalability beyond 16 nodes.
- Key for multi-generational clusters in the enterprise, but Cluster Sets must be all Windows Server HCI or Azure Stack HCI. These platforms cannot be mixed in a cluster set.
For more information about Cluster sets, see Microsoft documentation.
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