vMotion

                 vMotion is a feature that allows a running machine to be moved from one physical host to another physical host without having to power off the VM.

vMotion process

VM (vm1)-blade-5 (source)

VM (vm1)-blade-7 (Destination)

          1. The source Host (blade5) begins transfer the active memory pages to the destination host (blade 7) across a VMkernel interface. This is called pre-copy.

         During this the VM still service clients on the source (blade 5)

         The ongoing changes are written to a memory bitmap on source (blade 5)

         2. After entire contents of RAM transferred to the target (blade 7), then VM1 on the source host (blade 5) is quiesced. Still in memory not in service.

After that memory bitmap file is transferred to the target.

        3. The target Host (blade 7) reads the address in the memory bitmap file and request the contents of those address from the source (blade 5).

       4. After the contents of the memory referred to in the memory bitmap file have been transferred to the target host, the VMstarts on the Host.

 

vMotion Requirement.

a)      Shared storage for the VM files (a VMFS or NFS data store) that is accessible by both the source and target ESXi host.

b)      A Gigabit Ethernet or faster network interface card (NIC) with a VMkernel port defined and enabled for vMotion on each ESXi host.

c)      Both the source & destination host must be configured with identical virtual switches.

d)     Port group naming on both source and destination should be same and case sensitive.

e)      Processors of both hosts must be compatible.