USB Operating System?

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5 posts
by Dezazmondo » Tue Jun 19, 2012 12:21 pm
Hi guys,

I'm a total newcomer to linus and just recieved my Pi today (:D) but I have a question that the seach bar doesn't seem to answer (and I've not googled it yet).

Is it possible to boot from a USB with the Pi, or are we pretty much forced to use the SD card as a primary boot?

Sorry if this has already appeared in the forums, and yes I am aware there are only two USB ports bfore someone screams at me.

Cheers,
Dezza
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by jamesh » Tue Jun 19, 2012 12:27 pm
Theoretically you can do the initial boot using the SD card then move to the USB device for the rest. Not sure if it has been tried yet though.
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by Joe Schmoe » Tue Jun 19, 2012 1:08 pm
First of all, yes, the answer to the initial question is: You have to boot from the SD card. Basically, the contents of the "boot" (i.e., "FAT") partition on the SD card has to be on the SD card.

But...

jamesh wrote:Theoretically you can do the initial boot using the SD card then move to the USB device for the rest. Not sure if it has been tried yet though.


Oh, yes. It's been tried, done, and documented here in these forums (many times!)

To the OP: Think of the "boot" partition as being like the BIOS on a Windows/Intel PC. Think of the rest of the OS as being like the Windows OS itself. That "rest of the OS" can be on USB, with one caveat: The USB driver has to be in the kernel proper, not a module. This was a bugaboo in early releases of the images - USB was in a module, so you couldn't do this trick.

Note: It is also possible to boot from the network (someone has documented it here somewhere). Again, the initial boot (again, akin to the BIOS on a Windows/Intel PC) has to be on the SD card, but the rest of the OS is pulled from the network.
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by RaTTuS » Tue Jun 19, 2012 1:45 pm
on my Rpiboxed version [not complete yet .]
I have a 650Gb 2" Drive
4Gb SD card
5 port NIC hub
4 port USB hub
it's also overclocked to 900mhz

the SD card is used as the boot device but / is mounted from the USB drive
I could of used a smaller SD card but I don't own one
and I've not managed to stuff it all into a box yet - trying to work out the best layout ...

to answer the question asked
you have to boot from SD card but the rest can be on a proper HD
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by Dezazmondo » Tue Jun 19, 2012 2:12 pm
Thats brilliant!

Thanks for the replies guys. Things are starting to piece together in my head quite nicely now.

Looking forward to seeing what I can create with it :)
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