Product : VMware Inc, VMware Cloud Foundation/v3.0, Enterprise
Feature : Storage Scalability, Storage, Infrastructure Services
Content Owner:  Bhagyashri (Shri) Bhagvat
Summary
You can expand an existing vSAN cluster by adding hosts or devices to existing hosts without disrupting ongoing operations
Details
https://docs.vmware.com/en/VMware-vSphere/6.5/com.vmware.vsphere.virtualsan.doc/GUID-51AEE927-91A9-4B04-BF3F-DD7956D841A8.html