My Raspberry Pi experience (using Model 3B)

[fox]

I might be wrong, but my understanding of the usb issue is that the total amount of power supplied to the Rpi isn't relevant; it's the amount supplied to each usb port. I think that this is analogous to the issue of Apple iOS devices that get their power from lightning connectors. (I have an iPad Air 3, which uses lightning.) You can buy a lightning to usb 3 adapter, but it won't see a drive connected to it unless the adapter has a lightning port, and it is plugged into a power source. Even then, certain external drives with relatively large power draws (those containing HDs as opposed to SSDs), will not work.

[Jason]

I mentioned at the PLUG Mug last evening to Jason, that he could power his RPi from a battery power bank bought at the dollar store, instead of having to deal with the plug in power supply and long cord.
The specs on the dollar store power bank are, output 5V, 2.1 Amp (max) which is plenty of current for the RPi.  The power bank capacity is 4400 mAH, which should be ample enough for the 2 hours we are at Tim Hortons. :-)

That's a keen idea that I hadn't considered except that it wouldn't have removed my requisite for having had a power supply and long cord. Remember that it was accompanied by a 24" LED display. I'd like to see that run off a battery bank. Maybe if you put ten of them in parallel, it would work

I looked up the power requirements for Raspberry Pi 4B here. Although they recommend a 2.5 A power supply for the 3B, they also say in a question about batteries that you can power it from "devices are typically marketed as mobile phone emergency battery chargers." so yeah, it would probably work. But since I don't have a display that can also be powered from one, there's not much to gain from doing so.

I suppose I could use it as a headless display and then SSH or use VNC to control it from a PC or laptop. That might frighten the workers at Timmy's less who might have thought I was moving in. 

[Jason]

I might be wrong, but my understanding of the usb issue is that the total amount of power supplied to the Rpi isn't relevant; it's the amount supplied to each usb port. I think that this is analogous to the issue of Apple iOS devices that get their power from lightning connectors. (I have an iPad Air 3, which uses lightning.) You can buy a lightning to usb 3 adapter, but it won't see a drive connected to it unless the adapter has a lightning port, and it is plugged into a power source. Even then, certain external drives with relatively large power draws (those containing HDs as opposed to SSDs), will not work.

The link I just posted talks about this and you're right that a lot of it has to do with the draw on the USB ports. It mentions that you should "check the power rating of the devices you plan to connect to the Raspberry Pi and purchase a power supply accordingly. If you're not sure, we would advise you to buy a powered hub." It also mentions that the maximum allowed draw is 1.2 W for the USB ports combined (for the 3B and 4B). They tested the various models using a corded usb keyboard and mouse (I assume), HDMI monitor and wireless access and the 3B uses only 1.34 A under stress conditions (average is 0.85 A). So that's without any other USB devices.

[fox]

I hate to open the "boot from USB" issue again, but this morning I watched a YouTube video (here), which suggests that booting from a USB stick is much faster than booting from an SD card. The video is 3 years old, so things might have changed since then, as SD cards have become faster and Pi distros have become more streamlined. Having just switched my installation around to SD card booting from Noobs in place of USB booting from BerryBoot, I think that Raspbian actually runs faster on my Sandisk Ultra SD card than on my PNY 128gb USB3 drive. The aforementioned video also suggests that USB is more stable than SD cards and that the latter have a more limited lifespan, but I haven't used the Pi enough to have seen any negative effects of using the SD card. In my case, my data are kept on the USB drive, so I would imagine that this would greatly reduce any read/write wear on the SD card.

I was in a Rasberry Pi YouTube video mood this morning, and I watched two other videos comparing Raspbian to Ubuntu Mate. One of them (here) did speed tests between them, and even made a comparison with a regular PC. Both videos indicated that Raspbian is faster (about 20% in the tests), and in my experience, Raspbian was noticeably faster.

[Jason]

Just like with SD cards, thumb drives can vary quite a bit in performance. I tested my flash drives that I had at the time years ago and found surprising differences in performance. I realize that the drive you used is USB 3 but it could be that there is a separate chip for supporting USB 2 on it that isn't very good.

Regardless, you can test read/write speeds of drives using dd (sorry, Harry!). Remember to do the testing on the Pi as we don't know what corners they cut to make it small and cheap.

[fox]

Well apparently you can add other distros to Noobs after it is set up by holding the shift key the next time you boot. This is explained here.

Well I was somewhat wrong about that. With Noobs, holding the shift key does allow you to add or remove distros, but doing so rewrites the whole SD card, blowing away anything you added or customized in the distros present prior to this action. BerryBoot is more functional in that you can add distros without affecting the ones there, or you can remove an installed distro without affecting the others.

[fox]

Just like with SD cards, thumb drives can vary quite a bit in performance.
....

I just found an article (here) that not only verifies what you said, but actually shows that booting and opening files can be much slower when the OS is run from a usb3 drive than when it is run from an SD card. The tests were run on both a Pi3 and a Pi4, but both showed the same thing!

[fox]

...., you can test read/write speeds of drives using dd (sorry, Harry!). Remember to do the testing on the Pi as we don't know what corners they cut to make it small and cheap.

I did this and got 12.8 mb/s read speed and 7.8 mb/s write speed. I would have thought the SD card is about the same.

[Jason]

Just like with SD cards, thumb drives can vary quite a bit in performance.
....

I just found an article (here) that not only verifies what you said, but actually shows that booting and opening files can be much slower when the OS is run from a usb3 drive than when it is run from an SD card. The tests were run on both a Pi3 and a Pi4, but both showed the same thing!

Interesting. I did some testing using dd between the microSD card and one USB 2 drive. I'm going to try a few more drives and then publish the results in the forums in the next few days.