A Virtual Machine Essay

1265 Words6 Pages
INTRODUCTION Live migration is defined as the movement of a running virtual machine/an application among different physical machines without the client/application being disconnected. Memory, storage and networking of a virtual machine has to be migrated from source to the destination host machine. VM Memory migration: Following two techniques are used for movement of the memory state of a virtual machine from the source to the destination:- 1.pre-copy memory migration and 2.post-copy memory migration. Pre-copy memory migration: Warm-up phase- The Hypervisor copies all the memory pages from the source to destination, where at the same time the VM still runs on the source. If some memory pages change or they become 'dirty ' when the process is still on, they will get re-copied until the rate of re-copied pages is not less than the rate of page dirtying. Stop and copy phase- After the warm-up phase is completed, the VM will get stopped on the original host and the remaining dirty pages will get copied to the destination. Then the VM will resume on the destination. “Down-time”( The time taken between stopping the VM on the original host and resuming it on destination) ranges from a few milliseconds to seconds according to the memory size and applications running on the VM. Post-copy memory migration: Post-copy VM migration is carried out by suspending the VM at the source and then a minimum amount of subset of the execution state of the VM (CPU state, registers and
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