thegr8one
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How to boot from usb ?

Tue Jul 28, 2015 10:50 am

How can you boot from a usb pendrive on a pi ? I've got a b+ and a sd card with raspbian on it.
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DougieLawson
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Re: How to boot from usb ?

Tue Jul 28, 2015 11:16 am

You can't.

You can ONLY boot from an SDCard. You can move the root filesystem to a USB device but /boot MUST be on the SDCard.
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saksham2001
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Re: How to boot from usb ?

Tue Jul 28, 2015 12:30 pm

You can not. Raspberry Pi is defaulty made like this that it can only boot from an sd card.
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Joe Schmoe
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Re: How to boot from usb ?

Tue Jul 28, 2015 12:35 pm

Let's be fair here. Of course you can boot from USB - as long as you interpret that phrase correctly. It is understood that by "booting from USB", people mean that the OS is on a USB drive.

But people do understand, of course, that you still need an SD card for the initial phase of the boot.

Just as they understand that when you boot a PC, the initial phase of the boot process is in the BIOS. But they still say that they are "booting from the hard disk".
And some folks need to stop being fanboys and see the forest behind the trees.

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klricks
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Re: How to boot from usb ?

Tue Jul 28, 2015 12:43 pm

Here is a step by step guide on how to move the OS filesystem to a USB stick or hard disk: viewtopic.php?f=29&t=44177
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

W. H. Heydt
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Re: How to boot from usb ?

Tue Jul 28, 2015 2:56 pm

Joe Schmoe wrote:Let's be fair here. Of course you can boot from USB - as long as you interpret that phrase correctly. It is understood that by "booting from USB", people mean that the OS is on a USB drive.

But people do understand, of course, that you still need an SD card for the initial phase of the boot.
I'm afraid that I don't share your faith. From the tenor of the questions that pop up on the subject, I think there are a fair number of people who think that you can boot from a USB stick without using an SD card.
Just as they understand that when you boot a PC, the initial phase of the boot process is in the BIOS. But they still say that they are "booting from the hard disk".
Yabbut... The BIOS is part of the PCs hardware, in that the chips containing the BIOS code are physically part of the motherboard. The better analogy would be, I think, booting a PC from a USB stick or CD. That "looks" the same from a user perspective as "booting from the HDD". Therefore I suspect that at least some of those that ask the question are looking for an equivalence where USB on Pi == USB on PC, without understanding that there is no BIOS in the Pi that can handle multiple different boot devices. All that capability resides on the SD card.

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PeterO
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Re: How to boot from usb ?

Tue Jul 28, 2015 3:23 pm

Joe Schmoe wrote:Let's be fair here. Of course you can boot from USB - as long as you interpret that phrase correctly. It is understood that by "booting from USB", people mean that the OS is on a USB drive.
Not at all. What you are describing is mounting the root file system from the USB drive, which is a very different thing to booting from the USB drive. If you are going to try and add something to these thread please learn to use the correct/accepted words and not just make up your own interpretations.

But people do understand, of course, that you still need an SD card for the initial phase of the boot.
Is this the same kind of "understanding" you didn't show above ?

Just as they understand that when you boot a PC, the initial phase of the boot process is in the BIOS. But they still say that they are "booting from the hard disk".
So you think the BIOS part is important on a PC yet fail to mention the part played by the GPU in the PI boot process. :roll:

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Joe Schmoe
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Re: How to boot from usb ?

Tue Jul 28, 2015 3:33 pm

My point is that you should think of the SD card as being "part of the computer", not really a removable item. Just like the BIOS.

For this to work, of course, we need things to stabilize - so that you don't think you have to keep "upgrading" the SD card. I think we are (slowly) getting to that point.
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PeterO
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Re: How to boot from usb ?

Tue Jul 28, 2015 4:27 pm

Joe Schmoe wrote:My point is that you should think of the SD card as being "part of the computer", not really a removable item. Just like the BIOS.


Once again you are your own wrong interpretation of words and probably confusing people. The SD **IS** a removable device, to think of it otherwise is flying in the face of common sense ! :evil: :evil:

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W. H. Heydt
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Re: How to boot from usb ?

Tue Jul 28, 2015 4:38 pm

The only time the SD card *isn't* a (normally) removable part of the Pi is if you have a case that has to be disasembeled to get it out. As it happens, I have some cases like that (they include SD card covers). They are for use around children who might remove a microSD card and lose it when no one is looking. For use around adults, I use cases that permit easy removal of the SD card.

As for stability...there is stability and there is stability. The more astute PC users *do* update the BIOS periodically when the m/b manufacturer releases an update for it. Granted, *most* people don't do that and many probably don't know that it can even be done. For the Pi, the common recommendation is relatively frequent updates to the SD card even though relatively few updates to /boot are involved. Most updates are OS and package updates...much like any PC running a commercial OS.

Joe Schmoe
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Re: How to boot from usb ?

Tue Jul 28, 2015 4:47 pm

Most updates are OS and package updates...much like any PC running a commercial OS.
Yup. All true.
And some folks need to stop being fanboys and see the forest behind the trees.

(One of the best lines I've seen on this board lately)

Tom_A
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Re: How to boot from usb ?

Wed Jul 29, 2015 8:15 am

I've just written a guide for creating a USB install using Grsync instead of dd to copy the partition. This has several advantages, one of them being that you can copy the root file system while it is currently running.

USB Install Using Grsync

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