VMware vSphere live migration allows you to move an entire running virtual machine from one physical server to another, without downtime. The virtual machine retains its network identity and connections, ensuring a seamless migration process. Transfer the virtual machine’s active memory and precise execution state over a high-speed network, allowing the virtual machine to switch from running on the source vSphere host to the destination vSphere host.This entire process takes less than two seconds on a gigabit Ethernet network.
How does it work?
First, the entire state of a virtual machine is encapsulated by a set of files stored on shared storage such as Fibre Channel or iSCSI Storage Area Network (SAN) or Network Attached Storage (NAS). VMware vStorage VMFS allows multiple installations of VMware ESX to access the same virtual machine files concurrently.
Second, the active memory and precise execution state of the virtual machine is rapidly transferred over a high speed network, allowing the virtual machine to instantaneously switch from running on the source ESX host to the destination ESX host. VMotion keeps the transfer period imperceptible to users by keeping track of on-going memory transactions in a bitmap.
Third, the networks being used by the virtual machine are also virtualized by the underlying ESX host, ensuring that even after the migration, the virtual machine network identity and network connections are preserved. VMotion manages the virtual MAC address as part of the process. Once the destination machine is activated, VMotion pings the network router to ensure that it is aware of the new physical location of the virtual MAC address. Since the migration of a virtual machine with VMotion preserves the precise execution state, the network identity, and the active network connections, the result is zero downtime and no disruption to users.
Advantages of vMotion
- Perform hardware maintenance without scheduled downtime.
- Proactively migrate virtual machines away from failing or underperforming servers.
- Automatically optimize and allocate entire pools of resources for optimal hardware utilization and alignment with business priorities.