From a maintenance perspective, what is an advantage of server virtualization?

• A. It reduces energy usage by half.
• B. Hosts can be upgraded or replaced non-disruptively to the virtual machines running on the hosts.
• C. It eliminates backups.
• D. It automatically balances workloads across sites.

Answer: (B)

Virtualization lets virtual machines keep running even while the physical host is being serviced, upgraded, or replaced. This is done by live-migrating or moving VMs to other hosts, so the original hardware can be maintained without taking down the workloads. That makes maintenance windows shorter and less disruptive, which is the main advantage from a maintenance perspective. The statement that hosts can be upgraded or replaced non-disruptively to the virtual machines on those hosts best captures this benefit. Energy usage isn’t guaranteed to drop by a specific amount, backups are still required, and automatic workload balancing across sites isn’t an inherent, universal feature of virtualization without additional tools.