Make duplicate copy of bootable USB Flash Drive for VMWare ESXi

I am having Issues duplicating a USB flash drive running VMware ESXi 6.0 Update 3. I want to make backup copies in the event the production USB flash drive fails. I would like to know if anyone can share how they make images and copies. I am running VMware ESXi 6.0 update 3 on HP ProLiant Gen 9 servers.

I have tried the instructions at

I have verified my USB boot drive is mpx.vmhba32:C0:T0:L0, see below....

[root@ESXI04:~] ls -l /dev/disks
total 59049804611
-rw-------    1 root     root     16013942784 May  2 18:19 mpx.vmhba32:C0:T0:L0
-rw-------    1 root     root       4161536 May  2 18:19 mpx.vmhba32:C0:T0:L0:1
-rw-------    1 root     root     262127616 May  2 18:19 mpx.vmhba32:C0:T0:L0:5
-rw-------    1 root     root     262127616 May  2 18:19 mpx.vmhba32:C0:T0:L0:6
-rw-------    1 root     root     115326976 May  2 18:19 mpx.vmhba32:C0:T0:L0:7
-rw-------    1 root     root     299876352 May  2 18:19 mpx.vmhba32:C0:T0:L0:8
-rw-------    1 root     root     2684354560 May  2 18:19 mpx.vmhba32:C0:T0:L0:9

When I use the dd command to copy the image I get an error stating the mpx.vmhba32:C0:T0:L0 volume is not accessible.

I also tried using the USB Image Tool to backup the known good bootable USB flash drive to an .img file. I then used the USB Image Tool to restore the image to another identical USB flash drive. When I try to boot from the copy it fails to boot.
Mike MontgomeryInfrastructure ManagerAsked:
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Mike MontgomeryInfrastructure ManagerAuthor Commented:
Update, I tried using dd again to create an image from the boot drive on the ESXi host and this time it worked. I now have image files for my VMware host servers. Must have been a typo in the command that I overlooked. I will try creating the duplicate USB flash drive from the image file shortly and try to boot from it.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
dd is the only options, however this method is not supported, and you are far better backup and restore the ESXi configuration.

The biggest issue is finding a USB/SD card which is the exact same size, otherwise BOOT will fail. and even if you purchase two SanDisk 16GB USB flash drives, sectors can be different....

also read and write to USB flash drives is very slow, you would have installed ESXi (7-11mins) and Restored config, by the time you have written the image... and you've got to store the image somewhere!

We no longer create images, we install default (vanilla), and Restore the Config, and we make sure the configuration of the ESXi host is regularly backed up, if changes are made to the host!

Your question was previously discussed at length here

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Mike MontgomeryInfrastructure ManagerAuthor Commented:
Thanks Andrew, I do run backups now so I will follow your suggestion to create a vanilla install and restore.
Mike MontgomeryInfrastructure ManagerAuthor Commented:
The option to backup and restore the ESXi config and using a default install addresses my issue.
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