The vSAN Stretched Cluster feature was introduced in vSAN 6.1. Since then, this feature has matured nicely over the past several vSAN releases with thousands of stretched cluster configurations deployed worldwide. Now vSAN stretched clusters provide resilience to a variety of failure scenarios including drive, host, entire site, and network outages. The vSAN stretched cluster configuration is embedded in the vSphere user interface and it can be easily enabled for a vSAN cluster. A stretched cluster configuration provides redundancy and failure protection within each site and across sites.
The VM objects are replicated across both sites and synchronous writes are constantly updating the data at both locations. VMs running in a stretched cluster can be migrated from one site to another for planned maintenance without downtime using vMotion. In the case of unplanned downtime, vSphere HA and vSAN are tightly integrated to restart impacted VMs at the other site to minimize downtime.
Our vSAN team worked on adding a stretched cluster section within our vSAN infographic that helps you understand what happens in various failure scenarios. You can explore options for site failures and specific scenarios like ISL connection failures or temporary witness site unavailability. The infographic reveals the expected behavior and the impact to VMs depending on the selected failure scenario. This is a great way to evaluate if this configuration will be suitable for your business.
You can learn more about vSAN stretched cluster requirements, design considerations, and best practices in the vSAN Stretched Cluster Guide on StorageHub.