Purpose: How vMotion migration works?
First for migrating our virtual machines from over utilized source host to underutilized destination host we have to check whether both the hosts have the access to the shared datastore holding the VM’s files.
vMotion migration consists the following steps:
- VM’s memory state is copied over the vMotion network from the source to target host while during this users continuously access the VM’s and keep updating pages in the memory. The list of modified pages in memory is kept in a memory bitmap on the source host.
- After most of the VM’s memory is copied from the source to target host, the virtual memory is quiesced. No additional activity is occurred on the VM. In the quisced period vMotion transfers the virtual machine device
State and memory bitmap to the destination host.
- Immediately after the VM is quiesced on the source host ,the VM is initialized and starts running on the target host. A Reverse Address Resolution protocol (RARP) request notifies the subnet the virtual machines A’s MAC address is now on a new switch port.
- Users access the VM on the target host instead of source host no.
The memory pages that the VM was using on the source host are marked as free.