How VMotion Migration works?

Let's explore how VMotion migration works!

As we see our virtual machine is currently running on host 1 if we want to migrate that VM to host two using VMotion migration.

There are several requirements that we first need to meet as you can see between two host,

we need to have shared storage. the virtual machine files need to be stored in that shared storage and as a result of having shared storage the migration are actually very very quick because we need not copy any of the files,

well we actually need to be copy from the first host to the second host is the memory state of the virtual machine and that's performed across the network that we called VMotion network.

The VMotion network which we'll show you later during the segment is a private non routed, gigabit or faster network connection between the two hosts involved in the VMotion migration, now the virtual machine, on the other hand, see other networks such as

the network we have illustrated here the production network one of the requirements of the VMotion migration is that the host have the VMotion network but additionally, the

host need to have identical network configurations including identically spelled labels for the virtual machine port groups for a network such as the production network, so if the virtual machine port is called production with a capital P on the first host then the same virtual machine port group must have the exact same label on the second host it much be spelled production but with the capital P but with these pieces setup we can migrate the virtual machine from the host 1 to host 2 the way this is performed is that the host performs a bulk copy of the memory state of the virtual machine A from the first host to the second host across.

the VMotion network, while we perform that copy the challenge is that the memory location that were copying and changing, so what ends up happening if that initial bulk

copy is the VM is actually quest but the quiescing that the actual stopping of the VM is so quick that we as human don't perceive, during that period of quiescence,

the changes that occurred in the memory state are copied from the first host to the second host the VM is then unquestioned at that point VMS now on the second host,

the VM still at the same IP Address same mac address same hostname in fact from the outside world perspective nothings changed in that virtual machines expect

for one thing that virtual machine is now connected to a host which is plugged into a different physical port on the physical switch,

To address that issue we simply perform reverse ARP Broadcast and that act and the all other test we perform performed automatically for you behind the scenes the end result is you suddenly see the VM that was running on ESXi host 01 running on the second host