I've spent the past week playing with ESXi, specifically figuring out which hardware that's not on the official VMware HCL I could get the stuff to run on. First, I found that Dell PCs run ESXi beautifully, straight off a USB stick. I followed the directions out there for transferring from the install image to USB stick and that worked very well. But, I doubt my users are going to understand when I tell them their PCs have been commandeered to run my virtual machines...so...back to the data center.

After clearing out that little bug VMware had in one of their builds, I found that I could successfully install ESXi on the following hardware, none of which is on the HCL:

• SuperMicro SuperServer 5013C-i - These are probably 4 or 5 year old P4-based machines. I have three of them with 2-4GB of RAM each and a P4 3.2GHz CPU. The on-board SATA controller is the Intel ICH5R, which happens to be supported by the ata_piix driver present in the ESX(i) kernel. The catch is that the bios must be set up with SATA in "Enhanced" mode and note "legacy" mode, otherwise the SATA connections are seen as IDE drives, not SCSI drives, which prevents VMware from loading them correctly.

• SuperMicro X5DPA-TGM+ - This is a motherboard in a SuperChassis that I have here that has 2 x 2.8GHz Xeon processors and 4GB of RAM. It has an onboard Intel Pro 100 and an on-board Intel Pro 1000 ethernet interface, and runs ESXi remarkably well. I don't think I'll be running more than a handful of VMs on it at a time, but I'll take all the ESX(i) servers I can get! The on-board SATA controller is the Adaptec ICH6 controller, which is also supported under the ata_piix chipset. This has to be set up in the BIOS in "combined" mode with the SATA controller in "Native" mode in order for ESXi to see it correctly.

• SuperMicro X5DL8-GG -This is a PCI-X motherboard with 2 x 2.8 GHz Xeon processors. This one is a bit more challenging to get running, but I was able to do it at intermittent intervals. First, the on-board Adaptec SCSI controller is the 7902 chipset, which you would think would be supported under the aic79xx or aic7xxx module with ESXi. Unfortunately, these modules crash when loading, so you can't use the on-board SCSI controller. There's no on-board SATA controller, and IDE is out of the question for ESXi, so it has to be an add-in one. I have a couple of LSI Logic 22030-R cards that seemed to work okay. I was also able to boot off USB at one point, however my USB-based KVM system interferes with this older motherboard's ability to see the USB storage device correctly, so it only worked when I wasn't using the USB KVM. Of course, SuperMicro has stopped updating the BIOS for this MB, so there's little hope that USB BIOS support will ever work correctly on it, but maybe I'll be able to kludge my way around this one with the right combo of add-in controllers, USB devices, etc.

• Also got ESXi running on a whitebox Intel D865GLC motherboard with 1GB of RAM. The machine has a SATA controller but I booted it off a USB stick as I don't have a SATA disk in the machine. I'm guessing the SATA controller is probably compatible with the ata_piix module in ESXi, but we'll see - I may try that later. This machine has an Intel Pro 100 network card that is recognized by the e100 driver in ESXi. 2.4GHz processor.