A. When using a zero downtime solution such as Hyper-V's Live Migration or VMware's vMotion, a virtual machine(VM) is moved between virtualization hosts with no downtime. In reality, there's still a slight pause of the VM as any remaining memory and device states need to be moved to the new host. Also, a reverse Address Resolution Protocol (ARP) check needs to be done to let routers know where the VM now resides. This means if you were pinging a VM as it was migrated, you may see one or two packets lost, and this is normal. The key factor is the period of unavailability is less than the TCP connection timeout value, which means that while clients may see a slight pause, they won't be disconnected from the VM that's being migrated.
Related Reading:
- Virtualization Myths and Misconceptions
- Q. I'm seeing a big performance difference with my live migration operations when I use Cluster Shared Volumes (CSV), is this normal?
- Q. How can I list all applications being published from a Windows Virtual PC virtual machine (VM)?
- Q. Why are my virtual machines (VMs) migrated between nodes in a cluster using Quick Migration instead of Live Migration when I shut down a cluster node?
Check out hundreds more useful Q&As like this in John Savill's FAQ for Windows. Also, watch instructional videos made by John at ITTV.net.
