I’ve been upgrading my home VMware lab to vSphere 5.1 today and ran into an issue that I thought I would share. I had previously written about my home lab environment – I run HP xw8600 workstations, and because I’m using SATA disks behind a SAS controller they are being seen as ‘remote’ disks to the ESXi installer. This means that I need another type of disk that will be seen as a ‘local’ disk so ESXi can create a scratch partition. A USB thumb drive was the answer, but not without issues.
When I installed ESXi 5.0 on the thumb drive, the install completed without problem, but after the post-install reboot ESXi 5 failed to boot. I received a non-system disk / no bootable device error.
When I installed ESXi 5.1 on the same thumb drive, the install completed without problem, and again, after the post-install reboot ESXi failed to load. On ESXi 5.1, however, I didn’t receive an error, but just had a blinking cursor in the upper left corner of an otherwise blank screen. The cursor just blinked endlessly – no ESXi loaded.
The fix was the same for both 5.0 and 5.1, even though the symptoms were different. Because I’m running on vintage hardware, my BIOS does not support booting from GUID Partition Table (GPT) partitions. As of vSphere 5.0, VMware changed the partitioning layout of the system disk from Master Boot Record (MBR) to GPT. My motherboard does not have a UEFI option, so booting from GPT isn’t going to work. A GPT is not necessary on a 4GB thumb drive (GPT is necessary for partitions over 2.20TB), so the fix was to simply format my system disk as MBR. There is an install option in the ESXi installation routine to force the system disk to be formatted with MBR instead of GPT, enabling ESXi to boot correctly. Here’s how to enable ESXi to format the installation disk with MBR:
1.) Boot server from ESXi installation media.
2.) Wait for prompt in lower left-hand corner that says <SHIFT+O: Edit boot options> . Press SHIFT+O (that’s the letter O, not a zero).
3.) In the lower-left hand corner, after the word ‘runweasel’ insert a space then type formatwithmbr. Press enter to continue the installation process.
ESXi should now install as normal. After the install, you should find that your server (workstation) boots into ESXi. If it doesn’t, you may have to play with BIOS options a bit more. I’ve heard of AHCI mode causing issues with boot from USB, as well as incorrect boot order, and simply enabling the boot from USB option in BIOS. Aso, check to see if your server/workstation can support an EFI image instead of traditional BIOS.
If you are interested in some other ESXi boot options, see here: http://pubs.vmware.com/vsphere-50/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-50-installation-setup-guide.pdf.
When using the formatwithmbr option, the VMFS paritition created on the boot disk will be formatted as MBR. Any other VMFS partitions that are created on other disks in your system will be formatted with GPT per the vSphere Storage section in the official vSphere 5 documentation set.