I was doing some research for a client regarding ESX support on servers and it got me thinking of a chat I was having with a client. As ever what works and what is officially supported by the vendors sometimes differs. My client had asked if he could install VMware ESX 4.0 on his DL385 G1 to test functionality before upgrading his other servers, after some digging I found this post, do check it out.
When we say supported, that means if we log a call and ask for support the vendor will examine the issue without discussion and that the hardware has been validated as compatible and suitable for that operating system. The example being that you can install Windows 2003 on a Compaq Proliant DL380 G1, technically it may work but Microsoft and (or) HP may not recognize it as a supported configuration. Back to my client, could he install VMware ESX 4.0 on his DL385 G1 to check before upgrading, yes and it would work, however this is not a supported configuration therefore do it, sign off that you are happy with the configurations, the standards and the setup procedures but recognize that it might not properly replicate your production or real world platform going forward.