VMware made upgrading to vSphere 4 easy enough, but there are still a few things that can go wrong. One example is that admins must consider the patch and version levels of VirtualCenter and ESX to begin. After the vCenter upgrade specific compatibilities between vCenter 4 and ESX 3.x must be understood if a mixed mode environment will exist during the span of the upgrade.
vCenter 4 Pre-Upgrade Check
Although the Agent Pre-Upgrade Check Utility was introduced last Fall when VMware released vCenter 4 Update 1, I had not come across a situation where using the tool identified problems with ESX upgrades. Judging by several other blog posts that demonstrated the utility on the web already, most all of these bloggers showed “pass” scenarios as well. For me that was the same result until this week. In fact, the vCenter Pre-Upgrade Check proved it’s worth to me in a huge way.
For those not familiar how to use the Pre-Upgrade Utility, just start the autorun.exe in the vCenter 4 U1 .zip file or from the install DVD. At the bottom of the vCenter Installer menu is the option to start the pre-upgrade check. See the image to the right of this post.
Once the tool starts point it at the VirtualCenter 2.5 server. After less than 5 minutes