ESXi 6.5 to 7.0 Update 3 lessons learnt
In a quiet moment this week I decided to see if ESXi 7.0 would install on my two Dell PowerEdge T20’s as 6.7 wouldn’t play ball for me when I tried.
To my surprise 7.0 Update 3 did install on to the first box but when I came to reboot I got the dreaded “No Operating System Found” message. It took quite a bit of googling to work out what had happened but it would appear that I fell foul of an issue where the installer creates a broken FAT partition that causes the server to fail in UEFI boot.
Thankfully after trying different VMware fixes like copying around boot files I stumbled across the post ESXi 7.0.2 failing to boot in UEFI mode – a possible fix and major kudo’s to the user ChunkyBezel as it sorted my issue out. I used NomadBSD to create a USB stick and once fired up I fixed the boot partition using fsck_msdosfs, rebooted, and boom my host came back up in UEFI boot mode in the BIOS.
Along the way I did make several mistakes such as switching to legacy boot mode to see if that worked, flattening the disk which I installed ESXi on, and trying to restore a configuration backup from version 6.5 on to the freshly installed 7.0.
My second host was extremely straightforward in comparison with just performing an upgrade to 7.0 Update 3. The host failed to boot after the install but once I’d fixed the partition and rebooted it was back online and as it was.