I had an old MacMini lying around at home that used to be my media centre but has since been replaced by a Raspberry Pi.
The Mini is the first generation aluminium unibody Mid 2010 model. So its a MacMini4,1 with a 2.66Ghz Core 2 Duo and 4Gb RAM (Max. RAM is 8Gb according to Apple, but it has been proven to support 16Gb)
Its been well documented that running VMWare ESXi on MacMini’s is no problem, but I could find no evidence of anyone attempting to run ESXi on such an older model.
The first issue I had however was the RAM, 4GB isn’t going to be enough to allow the install of ESXi 5.5. So I went about trying to locate RAM for this model. Unfortunately finding 2x 8Gb PC3-8500 1066mhz ram sticks was next to impossible. OWC has a kit but it was insanely expensive once postage from the US was included.
However the newer PC-10600 1333Mhz RAM in 8Gb modules was pretty easily available. After much research I found that having both RAM slots occupied by 1333Mhz modules in this model mini would result in a failure to boot. So I went with the next best thing. 1x 8Gb 1333Mhz stick and 1x 4Gb 1066Mhz stick. Not ideal as its non matching pairs, however the performance drop of going from 128bit addressing to 64bit addressing doesn’t seem to make much difference for non graphics related tasks, so for an ESXi host its fine.
So now we have 12Gb of RAM in the Mini, enough to run a couple of OS X and Linux VM’s
Installing ESXi was a complete non-issue. Downloaded the latest ESXi ISO from VMWare, imaged it to a USB flash drive using UNetbootin Started the Mini up from the USB flash drive and went through the install process. I chose to install ESXi to another USB flash drive so that my internal hard drive in the mini could be used purely for a data store within VMWare. I used an 8Gb San Disk cruiser fit super low profile USB drive so that it doesn’t stick out of the back of the Mini too much.
After installing and setting a static IP on the host, I used the VSphere client software running on another Mac via a Windows 7 VM to setup ESXi and make my first VM on the Mini.
I had absolutely no trouble at all throughout this process, no need to edit or add in extra drivers or anything like that. So if you have an old Mac lying around and want to set up a small test lab chuck some RAM into it and give ESXi a go!
A great resource for running ESXi on Mac Hardware is here at Virtually Ghetto