When designing a Metro Volume, placing the witness at a third site is crucial to avoid unnecessary storage and compute resource usage. The witness helps in maintaining quorum and ensuring the consistency of the Metro Volume in case of a site failure. Here's how it works:
Witness at Third Site: Placing the witness at a separate, third site ensures that it can independently verify the status of the primary and secondary sites, maintaining high availability and failover capabilities without consuming significant resources.
Avoids Resource Usage: By offloading the witness function to a third site, the primary and secondary sites can focus their resources on storage and compute tasks without the overhead of managing quorum.