Boot from USB

Step 1 –  Download and install Raspbian image on the USB Flash and MicroSD

Step 2 – Enable usb boot option

sudo nano /boot/config.txt
Add program_usb_boot_mode=1


Step 3 - Reboot

Step 4 - Edit cmdline.txt

change line
"root=/dev/mmcblk0p2" to "root=/dev/sda2"

Step 5 - Shutdown raspberry pi

Step 6 - Plug usb flash and power on raspberry pi

Still needed sd card