Quoting TechTarget:

A utility that automates parts of the migration from VMware ESX 2.x to VMware Infrastructure 3 (VI3) is a leading candidate for inclusion in VMware Inc.'s next point release, 3.0.1. Some VMware observers believe the company will release it at its annual VMworld 2006 conference in early November.

News of the migration utility, dubbed "Dmotion" internally, was leaked by a participant on one of VMware's own technology network (VMTN) discussion forums. With it, users will be able to move a virtual machine (VM) running in an ESX 2.x environment to ESX 3 without taking it down. A VMware representative did confirm that the company is working on Dmotion, and is "targeting" it for inclusion in 3.0.1.

VMware would not comment on the specifics of how Dmotion works, but people familiar with it say it appears to work by creating a snapshot of a running virtual machine to which new changes are written, using VMotion to copy the VM to an ESX 3 environment and, finally, applying the changes in the snapshot.

The hot VM upgrade capability will also have some limitations, specifically:

• Movement between ESX 2.x and VI3 will be "one-way."
• Users will eventually need to reboot their virtual machines to upgrade the virtual hardware (from VM2 to VM3 format) and install VMware Tools. Until that work is complete, VI3 features such as Consolidated Backup, Distributed Resource Scheduler (DRS) and VMwareHA will not work.

VMTN participants responded positively to the prospect of hot VM migrations. "I just hope it comes out fairly soon," wrote "mstahl75," a systems engineer . "It took 6 1/2 hours to cold-migrate one our systems and we have another one that is twice the size of that. Hot-migrate would be great."

"Definitely worth the wait," wrote "d1c1ple," a senior systems engineer from New Jersey. "My co-worker and I sat in the VI3 update class a few weeks ago and our heads exploded when thinking of tackling one of our largest 2.5x farms. [This] should be a huge improvement if it works as advertised."

Indeed, the current process for moving from ESX 2 to 3 "isn't impossible -- it can be done -- but it's quite complex," said Mike Laverick, a freelance VMware instructor and trainer located in the U.K. and owner of the site www.rtfm-ed.co.uk.

According to a VMware white paper, "Planning an Upgrade to VMware Infrastructure 3", the move to VI3 involves upgrading these five key components:

• VirtualCenter, the management station, from 1.x to 2.x
• ESX Server, the hypervisor, from 2.x to 3.0
• VMFS, from VMFS 2 to VMFS 3
• The Virtual Machine files (from VM2 to VM3 format)
• VMware Tools

Read the rest of the article, here.