I pulled out my last SATA disk from my homelab whitebox.  The ESXi boot partition was on there.  My goal is to never use a spinning disk again, so I decided to try boot from USB.

I actually installed ESXi on the USB drive in VMware Fusion, then pulled it out and put it in my host to boot from.

I plugged the drive into a USB 3.0 port.  It booted, but it didn’t save any configuration changes when I rebooted.  I plugged it into a USB 2.0 port and the changes saved, but when I went to install drivers I received the following message:

[InstallationError]
There was an error checking file system on altbootbank, please see log for detail.
Please refer to the log file for more details.

Google pointed me to this KB article: Remediating an ESXi 5.x host with Update Manager fails with the error: There was an error checking file system on altbootbank (2033564) which did the trick with the following results:

/tmp # vmkfstools -P /altbootbank/
vfat-0.04 file system spanning 1 partitions.
File system label (if any):
Mode: private
Capacity 261853184 (63929 file blocks * 4096), 261066752 (63737 blocks) avail, max file size 0
UUID: 03a06fe6-945129df-35c7-0bb4da8a6324
Partitions spanned (on "disks"):
        mpx.vmhba32:C0:T0:L0:6
Is Native Snapshot Capable: NO

/tmp # dosfsck -a -w /dev/disks/mpx.vmhba32:C0:T0:L0:6
dosfsck 2.11, 12 Mar 2005, FAT32, LFN
/.Spotlight-V100/Store-V2/CBAD0E16-35BF-4279-81B1-45D156946301/.store.db
  File size is 102400 bytes, cluster chain length is > 102400 bytes.
  Truncating file to 102400 bytes.
Reclaimed 3 unused clusters (12288 bytes) in 2 chains.
Performing changes.
/dev/disks/mpx.vmhba32:C0:T0:L0:6: 53 files, 188/63929 clusters