You can stretch a vSAN cluster (ESA or OSA) in a workload domain across two availability zones within a region. Both availability zones must contain an equal number of hosts to ensure failover in case any of the availability zones goes down.
The default management vSphere cluster must be stretched before a VI workload domain cluster can be stretched. This ensures that the
NSX control plane and management VMs (vCenter,
NSX management cluster, and SDDC Manager) remain accessible if the stretched cluster in the primary availability zone goes down.
Note: You cannot stretch a cluster in the following conditions:
- The cluster is a vSAN Max cluster.
- The cluster has a vSAN remote datastore mounted on it.
- The cluster shares a vSAN Storage Policy with any other clusters.
- The cluster includes DPU-backed hosts.
Some use cases for stretching a cluster are described below.
- Planned maintenance
You can perform a planned maintenance on an availability zone without any downtime and then migrate the applications after the maintenance is completed.
- Automated recovery
Stretching a cluster automatically initiates VM restart and recovery, and has a low recovery time for the majority of unplanned failures.
- Disaster avoidance
With a stretched cluster, you can prevent service outages before an impending disaster.
