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Can I mix different hosts, controllers, drives, and so on in a cluster?
Consistent hardware and software configurations across all hosts in a vSAN cluster are recommended. However, mixing various host configurations in a vSAN cluster is supported as long as all components, firmware versions, drivers and so on are listed in the VMware Compatibility Guide for Systems/Servers and VMware Compatibility Guide for vSAN for the versions of vSphere and vSAN you are using. This flexibility enables organizations to upgrade and replace hosts and storage in an incremental fashion, which is commonly less expensive and easier than replacing entire storage arrays.
Recommendation : Implement consistent hardware and software configurations across all hosts in a vSAN cluster. Verify vMotion compatibility across all of the hosts in the cluster - see this VMware Knowledge Base (KB) Article: Enhanced vMotion Compatibility (EVC) processor support (1003212) .