Although VMware vSphere came out a couple of months ago, I haven't had the time to try it out yet. Today I took the opportunity to try and upgrade my ESXi 3.5 server to ESXi 4.0. This won't allow me to test out the new VMware features such as Fault Tolerence, but I'll be able to run the latest vSphere client and see how the interface has changed.
I was a bit reluctant to do this because installing ESXi 3.5 on the USB key drive inside my ML115 G5, although not complicated, consisted of a number of steps and manual copying of files (not to mention having to crawl under the desk and physically install the USB stick).
Well the good news is that ESXi 4.0 is a much easier story. The operating system can be installed from CD straight onto the USB key drive, so no need to pull the side off the case. The install is quick and takes about 5 minutes. Then a reboot and to the DOS-like menu that allows for the networking, password etc to be configured.
A download of the vSphere 4 client and registering the licence key (free for ESXi) and everything is ready to go. I re-added the iSCSI and NFS datastores from my OpenSolaris server and fired up the VMs.
I haven't done anything beyond this yet, but for an upgrade I assumed would be a hassle, ESXi 4.0 has been very straightforward.