The upgrading of a physical host is a natural process, which takes place when the system needs to catch up with demands. The administrators opt for a manual migration or duplication of the virtual machine to sustain a healthy environment. The virtualization techniques have eased the process by allowing workload posting from one host to another. The rise in cloud technologies have aided in the journey of live migration techniques that match up with the changing modern environment. Live migration is basically the way by which a working virtual machine or an application is switched from one physical host to the other, without any disruption on the client side or the application side.
Live migration allows smooth movement of all memory, network connectivity, and storage of the host machine to the destination machine. The process prevents any possible infrastructure or maintenance collapse. It is also responsible for removal of any downtime that might have occurred during maintenance or upgrading of the system. When the process of migration is carried out smoothly the end user remains completely unaware of the migration. The technology is an extremely useful technology that aids in proactive mending. The live migration techniques are being widely used by virtual machine managers like Microsoft’s Hyper-V, KVM, VMware vSphere, and Xen.
Live Migration Techniques
The live migration consists of two steps: the pre-copy migration and the post-copy migration stage. These have been developed to overcome any hurdle during the process of migration and to make the migration process smooth and effective.
- a) The pre-copy migration technique: In this method, a remote machine runs on an origin node and in between the memory is being constantly shifted to the destination node. When the duplication speed crosses the recording rate of the origin, the remote machine is shifted to the destination with minimum loss of time. This technique enables a double copy of the memory available on each node. This process, at times, leads to greater consumption of resources and time when there is elevated traffic.
- b) The post-copy migration technique: In this method, a remote machine is excluded from an origin node and in-between, the implementation state is shifted to the destination node. Following the method, the memory pages are immediately pushed from the origin node to the destination node leading to a stage called pre-paging. In this, when a remote machine in the destination mode attempts to access a non-transferred page, a message of page-fault is popped up that leads the requested page to be transferred to the target node on the spot. The technique is quicker than pre-copy stage, but no backup is available for this stage.
There are a number of organizations that help with the application migration to cloud, among them CloudEndure is notable. The Cloud Endure Migration Technology lowers the complication of migration and helps in combating risks associated with migration.
Undoubtedly, live migration is a revolution that is important to safeguard the overall environment of an organization. The process leads to enhanced utilization of resources and reduced electricity costs. The technology even enables enhanced operational efficiencies and excellent data center usage.