Which feature enables live migration of running virtual machines with no downtime?

Which feature enables live migration of running virtual machines with no downtime?

• A. Snapshots
• B. vMotion
• C. DRS
• D. HA

Answer: (B)

Live migration of a running virtual machine is achieved by a feature that streams the VM’s memory and state to another host while the VM keeps running, so you don’t have to power it off. This is what makes the move feel seamless to users. In practice, the migration starts by transferring the VM’s memory from the source host to the destination host while the VM continues to operate. The system then tracks memory pages that are being changed, repeating the transfer for those pages as needed. When most of the memory has been migrated and only a small amount is still changing, a very brief pause happens to transfer the final pages and CPU state, after which execution resumes on the new host. That brief interruption is typically imperceptible, giving the appearance of no downtime. Snapshots, while useful for capturing a VM’s state at a moment in time, are not used for moving running workloads. They preserve or rollback the VM’s state, not for live migration. The feature that does the actual moving is designed specifically for live migration. DRS is about automatically balancing compute load across hosts and may trigger migrations to optimize resources, but it’s the underlying live-migration capability that enables the move, not the balancing logic itself. HA focuses on keeping services available by restarting VMs on another host after a failure, not on moving a running VM without downtime.

Live migration of a running virtual machine is achieved by a feature that streams the VM’s memory and state to another host while the VM keeps running, so you don’t have to power it off. This is what makes the move feel seamless to users. In practice, the migration starts by transferring the VM’s memory from the source host to the destination host while the VM continues to operate. The system then tracks memory pages that are being changed, repeating the transfer for those pages as needed. When most of the memory has been migrated and only a small amount is still changing, a very brief pause happens to transfer the final pages and CPU state, after which execution resumes on the new host. That brief interruption is typically imperceptible, giving the appearance of no downtime.

Snapshots, while useful for capturing a VM’s state at a moment in time, are not used for moving running workloads. They preserve or rollback the VM’s state, not for live migration. The feature that does the actual moving is designed specifically for live migration. DRS is about automatically balancing compute load across hosts and may trigger migrations to optimize resources, but it’s the underlying live-migration capability that enables the move, not the balancing logic itself. HA focuses on keeping services available by restarting VMs on another host after a failure, not on moving a running VM without downtime.