3B+ booting from USB

[mikedefieslife]

As I understand it, to boot from usb on the 3B+ you simply create an image on your usb media, plug it into the Pi, then turn on the Pi.

Unfortunately this isn't work for me.

If for example, I take my SD card out and put it into a usb adapter, and try to boot from it, I first get the rainbow screen, then the grey screen with the Pi logo. After that the Pi cuts signal briefly to the display, then when it comes back it's a black screen. This is when booting from a good SD card that will boot perfectly find in the SD card slot.

Next I installed an image on a USB SSD. When I plug that into the Pi and try to boot, I get no monitor output at all. The Pi turns on, then a few seconds later I see the light on the SSD come on to show that it has power/is connected, and that is it. Nothing else happens. There's no signal to the monitor and no evidence that Pi is doing anything.

Am I missing something?

[DarkPlatinum]

Some operating systems do not support USB boot.

[mikedefieslife]

It's definitely not the distro where the SSD is concerned. I flashed a fresh download of Raspbian Stretch desktop.

For some unknown reason, I guess the pi just doesn't like the drive. Though when I'm running from the SD card slot, it will happy detect and mount the drive.

A fresh stretch image on an SD card plugged in via USB adapter does seem to work though.

There goes my plan of using an SSD for Raspbian it seems.

[Andyroo]

Welcome to my world of pain viewtopic.php?f=28&t=226711

So far SSD and HDD giving me issues. I know the Pi only has a limited space for USB boot code but trying to support multiple disk formats and not multiple devices seems counterintuitive and counterproductive. I would rather be forced into one boot disk format and have better device support Format is under user control where as device selection is less so when it’s a black box from a store...

[k-pi]

I too, have tried several different setups, SSD & HDD, none of them will boot from the USB sockets alone, seems there just isn't enough power for most disks - some people have been lucky, but the majority find they just can't boot disks from the power supplied from the USB sockets.

I'm hoping that the next RPi will have USB3, & that that will solve our problem, but it seems it will be a longish wait, as they have just released the RPi3A+ & I don't think it will be in the near future.

[W. H. Heydt]

I think there's some confusion here. Booting from a USB device has nothing to do with the OS. It has everything to do with the VC4. The OS kernel doesn't get control until *after* the VC4 has booted. That's also why there are restrictions of the file system type for the boot partition. The VC4 is limited. The OS can use any filesystem it wants.

The major issue with HDDs is the spin up time. Do some research on how to deal with those issues. The other major issue people are likely to run into is interface conversion, specifically between USB and SATA. Not all USB to SATA adapters "play nicely" with the Pi. And indeed, as can be seen in a thread in General, companies are prone to changing the internal electronics of such adapters leading to cases where one version of what is supposed to be the same model will work, and another version will not.

Probably about all that people can do is to get data on the specific conversion chip set is in their adapter and let others know which chips work and which don't. (We've been down this same road with WiFi dongles....)

[bctf1]

I also have had issues booting from different devices on my 3B+. In each case had a fresh install of raspbian stretch imaged with etcher. My SSD drive in a usb enclosure would not boot. I then got a new power supply rated at 5v &2.5a output. The ssd still would not boot, but a 2.5" laptop hdd in a usb enclosure and a usb thumb drive would boot using the new power supply.

I agree with the previous poster that picking a usb adapter/enclosure that works is a bit of a crap shoot. I think that the output of the PS is also very important. I am currently booting from a 64gb Samsung Select micro sd card. It seems to be fast enough for what I need. My only gripe is that I can't play Youtube videos at any resolution but that seem to be due to a storage bottleneck.

[HawaiianPi]

I've had good success booting Pi 3B and 3B+ computers from a variety of SSD and HDD models using a few different adapters.

The adapter cable I've had the best luck with is a USB 3.0 to SATA III cable by Eluteng, but unfortunately that adapter seems to have been recently replaced by a newer model that did not work as well when I tried it.

I also have an adapter cable by Sabrent which I've tested with several SSD drives, and an external enclosure by ORICO which I've tested with both SSD and HDD (names are links to Amazon USA).

My systems are powered by the official Raspberry Pi Universal Power Supply, and the drives are powered by the Pi USB port. Current Raspbian images are written directly to the SSD or HDD using Etcher, and my older 3B model has had the USB boot bit programmed.

As far as chipsets are concerned, it is, unfortunately more complicated than that. I have adapters with ASM1153 or JMS578 chips that do and don't work (same chips in different adapters). It's a combination of the chip and firmware in the adapter and the SATA drive, and how they interact with each other and the Pi boot-loader. It's possible to get combinations that don't work (no boot at all), partially work (cold boot fine, but fail on reboot), or work with some drives but not others (I have another adapter which works with my SP SSD but doesn't like my Samsung).

Yes, it is a bit of a crapshoot, but things have improved over the years, and compatibility is better now. The newer 3B+ has an improved boot-loader, and the Raspbian firmware has also fixed some issues. It's still not perfect, but it is much better than it used to be.

[mikedefieslife]

What sort of speeds have you been getting from your SSD vs SD Card?

My last test (using DD) of my A1 Sandisk SD was around 19 MB/s write and 23 MB/s read.

It's not the speed that I'm training to attain by going SSD (it's still limited by being USB3) it's the robustness.

[HawaiianPi]

Booting from USB takes longer, but once up and running the SSD feels faster than a SanDisk Ultra A1 micro SD card. I've been meaning to do some proper benchmarks, but haven't gotten around to it yet. However, the SSD will have higher random I/O (IOPS), so it's not really a surprise it performs better. The raw throughput will be limited by the USB 2.0 interface of the Pi, but higher IOPS is where the SSD shines.

Since SSD prices have fallen faster than micro SD cards, SSD is actually a good idea for systems that need more than 64GB of storage. Current SSD pricing puts 128GB drives only slightly higher than A1 rated micro SD cards, and in larger sizes the SSD is actually less expensive. I have SSD models from Samsung (850 EVO), Crucial (MX500), Silicon Power (A55) and MyDigitalSSD (SB2), and at one point or another I have tested them all on my Pi 3B(+) with the Eluteng and Sabrent adapters. I have also tried a 500GB Western Digital HDD on the Eluteng adapter cable and the Orico enclosure.

Also note that some additional testing I've been doing with the new ELUTENG indicates it may be okay after all. Keep an eye on the following thread for details: viewtopic.php?f=63&t=227600

[grimjaw]

Booting from USB takes longer

I have a project where I need the absolute fastest boot time I can get. I know that on some RPi models, the bootloader looks for an SD card even when booting from USB. I'm guessing that is what you are referring to here. Is there anyway around that on the 3B+? I have read that putting an empty SD card in the slot will reduce the delay, but can it be completely eliminated?

I have a 3B, but before I permanently fuse the OTP bit, I'd like to find out if it will still look for an SD card even after the bit is fused. Do you know?

Thanks!

[fruitoftheloom]

Booting from USB takes longer

I have a project where I need the absolute fastest boot time I can get. I know that on some RPi models, the bootloader looks for an SD card even when booting from USB. I'm guessing that is what you are referring to here. Is there anyway around that on the 3B+? I have read that putting an empty SD card in the slot will reduce the delay, but can it be completely eliminated?

I have a 3B, but before I permanently fuse the OTP bit, I'd like to find out if it will still look for an SD card even after the bit is fused. Do you know?

Thanks!

That is covered in the HELP section here:

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

[rpdom]

I have a 3B, but before I permanently fuse the OTP bit, I'd like to find out if it will still look for an SD card even after the bit is fused. Do you know?

That is covered in the HELP section here:

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

Or you could have just said "Yes", which is true unless certain other OTP bits have been set too.

[HawaiianPi]

I get much faster boot from an A1 rated micro SD card. A2 cards may be faster, but I doubt the difference would be much.

I have not tried setting the additional OTP bits to control the boot device from GPIO. In theory this should reduce USB boot times, but it may not be enough to beat SD card boot (USB has more system overhead and is shared with the Ethernet port).

Also, finding compatible USB boot drives is an ongoing issue, as detailed internal specs of most USB drives are not published and tend to change over time. I recently tried to re-order a USB SATA adapter I've had good luck with by clicking the buy it again link in my order history, and received a newer model that no longer worked as well.

If you want the fastest boot time possible you should look into the CM3 with eMMC on-board. I have no experience with that myself. Perhaps someone else here can comment on CM3 boot time?

[grimjaw]

Thanks for the replies. @rpdom, sometimes we can't seem to find the answers even when they are right under our noses. Thanks for the link. I think that is just the info I needed.

@HawaiianPi, yeah, finding the right USB stick will be a project on it's own. Thanks!