Windows Server Failover Clustering (WSFC) can be a great fit for clustering applications and services on Microsoft Windows. Application and service availability with WSFC is just as important today as it was when Microsoft Clustering Services (MSCS) was first introduced. VMware vSphere has provided additional flexibility and choice that augments and extends the capabilities of WSFC for quite some time. VMware KB article 2147661 details supported configurations when using vSphere and WSFC.
One of the most recent updates to KB Article 2147661 included adding native vSAN support for WSFC requiring shared disks when using vSAN 6.7 Update 3.
What about vSAN Stretched Clusters?
This question has come up several times since VMware announced native vmdk support with SCSI3-PR for WSFC. This is an important question because it could extend the capability of WSFC across sites very easily.
vSAN Stretched Clusters already provide a proven and cost-effective solution for active-active data across sites, that is easy to deploy and operate with any additional hardware or appliances. WSFC shared disks can easily be shared by different WSFC nodes residing in completely different sites when using vSAN Stretched Clusters.
It is important to remember that vSAN handles data availability in Stretched Clusters based on Storage Policy while vSphere HA/DRS handle virtual machine availability.
- With each node of a WSFC cluster residing in alternate sites
- VM/Host rules can be used to ensure anti-site-affinity for these nodes
- A Storage Policy configured for protection across sites.
- If it is desirable for a WSFC cluster to run only in a single site
- VM/Host and VM-anti-affinity rules could be used
- A Storage Policy configured for protection in each site or only in a single site
Summary
Shared disks for WSFC on vSAN is supported in traditional, Stretched Cluster, or 2 Node vSAN configurations. When deploying WSFC on vSAN, stretched or otherwise, it is important to consider each potential failure scenario at the virtualization, Guest OS, or clustered application layer, selecting the most appropriate combination for the required use case.
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