Updating ESX To vSphere 4

It's no secret that the latest version of VMware's virtual infrastructure is bigger, better, faster and more capable than ever, but along with the new feature set comes a whole load of complexity. vSphere 4.0 has a ton of features designed to bring system performance to the next level, but it requires a little tweaking to get the most out of them.

Upgrading vSphere is cake, but your job is not necessarily finished. Virtual machines are not automatically updated to the new machine format when you update your hosts. A word of caution: vSphere virtual machines can only run on vSphere hosts. Don't complete the steps below until you are committed to bringing your entire cluster up to current. 

To get started:

Now that your machines have up-to-date virtual hardware, you can take advantage of the new networking and SCSI adapter types in virtual hardware. VMware made a number of enhancements to virtual networking with vSphere 4. While you're taking advantage of the networking enhancements, read Scott Lowe's awesome post on enabling jumbo frames for vDS, if you haven't already. The virtual networking adapter has performance increases of up to 85 percent over ESX 3.5, especially when multiple VMs are transmitting. I'm not sure if there is an easier way, but you can't seem to upgrade the network adapters to VMXNET3 directly.

To get around this:

You'll notice as soon as you login that a whole bunch of new hardware is going to be detected. Some machines also request a disk consistency check on startup prior to login. I let these run and have yet to run into problems. Once new hardware is finished installing, give the machine a reboot or answer in the affirmative to the reboot prompts.

After a successful restart on windows machines, you should see the original network adapters plus any new ones. Reassign any static IP addresses to the new VMXNET3 network interface and disable the original one. Bring the machine down for one more reboot and remove the original Ethernet adapter. When you power your server on, you are officially on VMXNET3. Just remember, VMXNET3 performance increases depend on all of your machines making use of the new networking technology, so get cracking and get the rest of those machines up to date.