Just upgraded some of my Lab hardware, now to install 6.7 on a newer Dell R630 without a CDROM we need to copy the installer to USB stick.    I prefer using Linux, and the default instructions at VMware fail to work on Ubuntu 18.04,  so here is the solution I found for Ubuntu 18.04

• Install Syslinux 3.86 on your Ubuntu ( latest version of Syslinux  in Ubuntu repos doesn’t work with ESX )
  • http://cciesp-jrny.blogspot.com/2018/11/how-to-make-bootable-esxi-67-usb-stick.html
• Then continue with VMware instructions to put syslinux on USB, copy MBR, and then copy the VMware files from the ISO on the USB ( but skip the edit step on syslinux.cfg   See:
  • https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.esxi.install.doc/GUID-33C3E7D5-20D0-4F84-B2E3-5CD33D32EAA8.html

TLDR;  Summary

If your comfortable with Linux ,  here is a summary of the steps above.

• Unzip SysLinux into a directory from here.
• Use Fdisk to prepare USB drive
  • Remove all partitions
  • Create new partition #1, type ‘c’ (FAT 32),  activate partition, write.
• Install  from Syslinux3.86 download directory.

  cd ~/Downloads/syslinux-3.86
  mtools/syslinux /dev/sdb1
  cat mbr/mbr.bin > /dev/sdb

• Create FS on USB

  /sbin/mkfs.vfat -F 32 -n USB /dev/sdb1

• Copy VMware ISO contents to USB ( if usb is on sdb1 ) and rename isolinux.cfg

  mkdir /usbdisk
  mount /dev/sdb1 /usbdisk
  
  mkdir /esxi_cdrom
  mount -o loop VMware-VMvisor-Installer-6.x.x-XXXXXX.x86_64.iso /esxi_cdrom
  
  cp -r /esxi_cdrom/* /usbdisk
  
  mv /usbdisk/isolinux.cfg /usbdisk/syslinux.cfg

•  Note skip the VMware step of editing syslinux.cfg file contents
• Unmount

  umount /usbdisk
  
  umount /esxi_cdrom