Upgrade VMs, migrate to ESX?
Today we are running 15 VMware workstation hosts in our environment, with five to eight Virtual Machines (VMs) on each host. Most of the VMs are in production. We are planning to move to VMware infrastructure three with new hardware (with SAN connections) over two data centers.

I haven't upgraded some VMs on the VMware Workstation 5.5 hosts in order to use the new features, because I am afraid I won't be able to migrate these VMs to ESX 3.0 after they have been upgraded. Am I right, or can go ahead and upgrade them?

The short answer to your questions is yes, you can go ahead and upgrade your workstation 5.5 VMs and still migrate them to ESX 3. The reason you could not upgrade the same VMs and migrate them to ESX 2.x is because of their generational affiliation. All VMware products are members of a "generation." VMware Workstation 5.x and ESX 3 are generation five VMware products. I know it can be confusing, especially since the product's version number does not relate to its generational affiliation (ESX 2.x is a generation four product).

VMware actually has a short 24-page white paper on this very topic entitled "Virtual Machine Mobility Planning Guide." It is a very good read, and I highly recommend it. You can find the latest version of the mobility planning guide at www.vmware.com/pdf/mobility_guide.pdf.

This was first published in June 2006