ESXi Not Booting from USB

To my understanding, the method is pretty straight-forward.

No vSphere server method (i.e. stand-alone):

1. Manually grab config you need (IP address, any hardware-config details like VLAN, NTP configs if any) via vSphere client.
2. Configure BIOS to boot from USB before HD.
3. Boot to USB.
4. Connect to the ESXi instance via vSphere client
5. Add in the config grabbed in step 1 as appropriate
6. Perform a Rescan Devices from Storage Adapters to locate any VMFS volumes.
7. Browse the newly discovered Data Stores.
8. When you find .vmx files, right click and select "Import into inventory"

vSphere method with vMotion:

1. Migrate all VMs off of the ESXi server.
2. Manually grab any special config you need (VLAN config being most important, NTP)
3. In vSphere, Disconnect the host, then delete it.
4. Configure BIOS to boot from USB before HD.
5. Boot to USB.
6. In vSphere, Add Host, and pick the hostname and login info for the USB-ESXi you created.
7. Manually enter the config grabbed in step 2 as appropriate.
8. Rescan your storage adapters for VMFS volumes.
9. Migrate a VM to this server to make sure it works.

vSphere method without vMotion (uncommon, but could happen):

1. Manually grab any special config you need (VLAN config being most important, NTP)
2. Turn off all VMs on the machine.
3. Follow steps 3-8 of the "with vMotion" checklist.
4. Follow steps 7-8 of the "no vSphere" method.

Note: When you disconnect the host, associated VMs will go into 'Orphan'. It is possible that when you do the Rescan Devices they'll all come back and there will be no need to do step 4.

Here's the process I used to resolve this:

VMware ESXi can be installed in an embedded mode or an installable mode. As outlined here, the installation mode is determined by the destination media and the size of the volume available to the ESXi installer.

• USB, SDHC or any device less than 5GB in size: Embedded
• Hard drives/volumes greater than or equal to 5GB in size: Installable

One of the unique attributes of running ESXi in embedded mode is that the OS is loaded into RAM and only touches the USB/SD device hourly during normal operation. In my situation, the system continued to operate, even with a failed SDHC device.

The error message I received in the vCenter interface indicated that configuration changes would not be saved, but the cluster was still usable. I left the system in this state for several days until I could get to the datacenter to replace the SD card.

With regard to steps to take following a failure of a USB or SD device, it is important to extract and save a copy of your host's settings!!

This is easily accomplished via PowerCLI or the vSphere CLI. I used PowerCLI running from the vCenter server:

Get-VMHostFirmware -VMHost 10.10.8.22 -BackupConfiguration -DestinationPath C:\Users\ewwhite\Downloads

• Following that, I evacuated all virtual machines from the affected host and placed it in maintenance mode.
• The host was then shut down, the SDHC card replaced with a new device, and I installed ESXi again.
• Once the host was up again with a fresh ESXi install, I made the bare minimum configuration changes needed to make the host visible on the network; set IP information, vlan info and password.
• I reloaded the saved configuration to the host via PowerCLI...

For this step, I used:

Set-VMHostFirmware -VMHost 10.10.8.22 -Restore -SourcePath c:\Users\ewwhite\configBundle-10.10.8.22.tgz -HostUser root -HostPassword YoMama!!

Restoring the configuration forces a host reboot. Once up again, I was able to issue a reconnect to rejoin the host in vCenter and exit maintenance mode.

If PowerCLI not available, the ESXi shell commands look like:

vim-cmd hostsvc/firmware/backup_config 

This produces a web link that you'll be able to browse to and download a tarball of the host's configuration.

You can SCP a configuration file to a host and use the following to restore the settings.

vim-cmd hostsvc/firmware/restore_config /tmp/configBundle.tgz

That's all!