Edelweiss - Fotolia

Q
Get started Bring yourself up to speed with our introductory content.

What advantages do Windows Server cluster sets offer?

Administrators don't need to stress about workload uptime with a new Windows Server 2019 clustering feature, which makes sharing resources and moving VMs easier.

Failure in the data center is inevitable, but a new feature called Windows Server cluster sets tries to keep those disruptions to a minimum.

Clustering has long been a staple of workload resilience in the data center. Applications in a cluster operate across multiple redundant instances to share the load to keep things running, even when a node in the cluster fails. Until recently, the technology has been limited in scope, architecture and resources. Windows Server 2019 introduces more sophisticated clustering, referred to as cluster sets, for highly scalable software-defined data centers.

Windows Server cluster sets combine clusters into a common logical fabric that can span facilities and geographic regions. Each cluster within the fabric retains independent resiliency, but provides greater fluidity and a unified storage namespace to share VMs and other resources across the greater fabric.

How cluster sets increase resiliency

The goal of cluster sets is to support scale-out -- rather than scale-up -- capability. Consider a typical cluster: If the storage or memory resources start to run low, the administrator must scale up the cluster by adding more resources.

However, that isn't always a simple proposition. For example, adding storage may affect rebuild times, and it may be impossible to add more memory on hosts with full dual in-line memory module slots. Adding more nodes or redesigning an entirely new cluster is often expensive and undesirable.

Windows Server cluster sets combine multiple clusters into a fabric, so member clusters can share resources, such as storage and memory. This scale-out behavior reduces costs and adds flexibility to clustering without compromising the resiliency of the individual member clusters.

For example, a cluster that uses storage technology such as Storage Spaces Direct can survive the loss of two nodes. Thus, a cluster with four nodes will fail if three nodes fail. Yet, a cluster with eight nodes will also fail if three nodes fail. By comparison, in Windows Server 2019's cluster sets, two clusters with four nodes each can still function if the same three nodes crash.

Combining clusters into a greater fabric doesn't necessarily improve the hardiness of individual member clusters, but establishing a fabric of clusters and sharing resources can provide better resilience across the overall fabric. The fault boundary does not extend beyond the member cluster where the fault occurs.

Cluster sets break previous hardware restrictions

Windows Server cluster sets combine clusters into a common logical fabric that can span facilities and geographic regions.

At a low level, cluster sets can ease the limitations posed by cluster hardware requirements. For example, typical clusters require closely matched processor capabilities. However, those requirements do not extend across the entire fabric.

It is possible to create one cluster of older hardware and another cluster of newer hardware, and then join both clusters using Windows Server 2019 cluster sets. This can help organizations looking to repurpose or extend the lifecycle of existing hardware, while mitigating the investment in new hardware.

At a higher level, a cluster set can include clusters located in different physical areas to implement cloud-like availability sets or availability zones.

Cluster sets ease VM management

Windows Server cluster sets can simplify cluster management. Once an administrator establishes the cluster fabric with a unified namespace, they can use centralized cluster management to select the cluster and node best suited to handle a new VM based on the requirements and each cluster's available resources. Conversely, admins can tag VMs with specific needs to utilize predetermined clusters.

IT pros can move VMs between member clusters, while the individual cluster will determine which node should receive the VM. This behavior can benefit administrators with tasks such as transferring all VMs off an aged cluster before decommissioning it.

Dig Deeper on Microsoft Windows Server 2019

Have a question for an expert?

Please add a title for your question

Get answers from a TechTarget expert on whatever's puzzling you.

You will be able to add details on the next page.

Join the conversation

3 comments

Send me notifications when other members comment.

Please create a username to comment.

What are your thoughts on the cluster sets feature in Windows Server 2019?
Cancel
Here is something that I haven't doc'ed but keep meaning to.  One of the features of Cluster Sets is the ability to over provision clusters.  On traditional Cluster, if you drain a node and the other nodes cannot handle all the VMs, lower priority VMs are shut down to make room for higher priority.  Unless you use the -VMFailoverMode parameter.  With this parameter, if VMs will not all fit on the other nodes, Cluster Sets will live migrate them to another Cluster in the set.  It can also move them back when the node returns.

To enable automatic cross cluster drain on a cluster set you can use:

    Set-ClusterSet -VMFailoverMode 1

Or, to enable without failback:

    Set-ClusterSet -VMFailoverMode 2

You can see the property updated with

    Get-ClusterSet | fl *

@johnmarlin_msft
MSFT PM that owns Cluster Sets
Cancel
Thank you for the explainer! 
Cancel

-ADS BY GOOGLE

SearchServerVirtualization

SearchCloudComputing

SearchSQLServer

SearchEnterpriseDesktop

SearchVirtualDesktop

Close