How vMotion Works ?

What is vMotion?

  • vMotion  enables live migration of a running virtual machine between ESXi Hosts
  • It is transparent to the Virtual Machine’s OS and applications.
  • Invaluable tool to admin to achieve the followings;
    • Avoid Server Downtime
    • Allow Troubleshooting
    • Provide Flexibility
  • Key enabler of DRS, DPM, and FT

vMotion works

What needs to be migrated?

  • Processor and devices state  – CPU, Network, SVGA
  • Disk – Use shared storage between source and destination
  • Memory – Pre copy memory while Virtual Machine is running

How vMotion Works?

  • Quiesce Virtual Machine on source machine.
  • Transfer memory and device state(checkpoint) from source to destination.
  • Resume Virtual Machine on Destination
  • Copy remainder of memory from source to destination
  • Free Virtual Machine resources on source machine.

vMotion Step by Step

Other Interesting Facts, Problems, and Troubleshooting: –

  • Virtual  Machine remains suspended during memory transfer
  • Copying Virtual Machine with large memory size may problematic.
  • 64 GB Virtual Machine requires around 57 seconds on 10 GbE NIC.
  • VMotion will check the remote system to make sure there is enough RAM and CPU before it begins the process.

Troubleshooting: –

  • Migration ID is same on source and destination.
    • Go to VMkernel log (/var/log/vmkernel.log)
    • Grep the migration ID for all vMotion related timing and statistics.

That’s it from here. Stay connected.