Consider these guidelines when working with a vSAN stretched cluster.

  • Configure DRS settings for the stretched cluster.

    • DRS must be enabled on the cluster. If you place DRS in partially automated mode, you can control which VMs to migrate to each site.

    • Create two host groups, one for the preferred site and one for the secondary site.

    • Create two VM groups, one to hold the VMs on the preferred site and one to hold the VMs on the secondary site.

    • Create two VM-Host affinity rules that map VMs-to-host groups, and specify which VMs and hosts reside in the preferred site and which VMs and hosts reside in the secondary site.

    • Configure VM-Host affinity rules to perform the initial placement of VMs in the cluster.

  • Configure HA settings for the stretched cluster.

    • HA must be enabled on the cluster.

    • HA rule settings should respect VM-Host affinity rules during failover.

    • Disable HA datastore heartbeats.

  • Stretched clusters require on-disk format 2.0 or later. If necessary, upgrade the on-disk format before configuring a stretched cluster. See Upgrade vSAN Disk Format Using vSphere Web Client.

  • Configure the Primary level of failures to tolerate to 1 for stretched clusters.

  • vSAN stretched clusters do not support symmetric multiprocessing fault tolerance (SMP-FT).

  • When a host is disconnected or not responding, you cannot add or remove the witness host. This limitation ensures that vSAN collects enough information from all hosts before initiating reconfiguration operations.

  • Using esxcli to add or remove hosts is not supported for stretched clusters.