Booting from USB

[TheKox25]

Hi, I have thought of enabling "Mass Storage booting" on my Raspberry Pi 3. From what I've read that process is irreversible. Does that mean that I will be able to boot from USB and no more from SD card? Or I'll be able to boot from USB or SD card?

[fruitoftheloom]

Hi, I have thought of enabling "Mass Storage booting" on my Raspberry Pi 3. From what I've read that process is irreversible. Does that mean that I will be able to boot from USB and no more from SD card? Or I'll be able to boot from USB or SD card?

Boot Flow

https://www.raspberrypi.org/documentati ... bootmodes/

[HawaiianPi]

You will still be able to boot from an SD card.

The Pi3 will check for a boot SD card first, before booting from a USB device. If no boot SD card is found in 5 seconds, then it looks for a boot USB device. So even if the boot USB device is still connected, inserting an SD card will override it.

Also note that not all USB devices are compatible with the simple Pi3 bootloader. Of the various devices I tried, none worked reliably for me, so I have gone back to the older method of having it boot from an SD card, then load and run the OS from an SSD drive. I am still able to do that, even after setting the OTP bit that enabled USB booting. I can also insert a stand alone boot SD card and my SSD will not be used at all.

[W. H. Heydt]

You will still be able to boot from an SD card.

The Pi3 will check for a boot SD card first, before booting from a USB device. If no boot SD card is found in 5 seconds, then it looks for a boot USB device. So even if the boot USB device is still connected, inserting an SD card will override it.

Also note that not all USB devices are compatible with the simple Pi3 bootloader. Of the various devices I tried, none worked reliably for me, so I have gone back to the older method of having it boot from an SD card, then load and run the OS from an SSD drive. I am still able to do that, even after setting the OTP bit that enabled USB booting. I can also insert a stand alone boot SD card and my SSD will not be used at all.

I've using a WD 314GB PiDrive with no issues, as well and a CM3L (the "guts" of a Pi3B in a small form factor) in a WD SATA adapter booting from an SSD. Both have been reliable.

[HawaiianPi]

I've using a WD 314GB PiDrive with no issues, as well and a CM3L (the "guts" of a Pi3B in a small form factor) in a WD SATA adapter booting from an SSD. Both have been reliable.

Yup, some devices work fine. Just none that I have tried. There is a small list of compatible devices in the documentation. In my case I tried an SSD on an mSATA-USB adapter, a couple of different flash drives and a USB HDD. Most of them booted fine but had problems with restart and/or shutdown. I've seen others post about similar problems, so my experience is not unique.

I'm sure if i tried every USB MSD in my rather extensive collection I could find something that worked, but I'm fine with leaving /boot on the SD card and running the OS from SSD. It's 100% reliable (boot, restart and shutdown all function as expected), and the boot time is actually quicker since there is no 5 second SD card timeout.

Supposedly there is a way to set another OTP bit and skip the SD check with some GPIO pins, which I may look into eventually, but for now it works and I have other things with higher priorities at the moment.

[willirl]

Can you please tell me how to set up everything to do the boot from the sd and get the OS from an ssd?

[RonR]

Can you please tell me how to set up everything to do the boot from the sd and get the OS from an ssd?

viewtopic.php?f=29&t=196778

[stuartiannaylor]

Just been having a look at https://ubuntu-mate.org/raspberry-pi/ub ... xt4.img.xz and seems to be fine on a USB stick.

Just wondering is there a way to force USB even when a SD card with OS is in place?

[HawaiianPi]

Just wondering is there a way to force USB even when a SD card with OS is in place?

The default is to boot from SD card first. You can only change that by setting an additional OPT bit, and then your system will not boot at all unless you pull certain GPIO pins high or low to tell it to boot from either USB or SD card.

https://www.raspberrypi.org/documentati ... ootflow.md

[stuartiannaylor]

Just wondering is there a way to force USB even when a SD card with OS is in place?

The default is to boot from SD card first. You can only change that by setting an additional OPT bit, and then your system will not boot at all unless you pull certain GPIO pins high or low to tell it to boot from either USB or SD card.

https://www.raspberrypi.org/documentati ... ootflow.md

Thanks.