Booting from a USB

I wanted to try booting from a USB for testing new opensuse releases (including beta and pre-beta releases).  I had been testing or installing new releases from CD or DVD.  However, burning a CD or a DVD has always seemed a fragile operation.  And since the released isos are usable with USB boot (perhaps after running “isohybrid” on them), it seemed like a good idea to give it a try.  So I purchased an 8G flash drive, which is large enough for a DVD iso.

Fortunately, my main systems (desktop and laptop) are new enough to support booting from USB.  It simply requires a tweak in BIOS settings, and they are ready to go.  But I also have an older laptop that I have relegated to test use, and there is an even older system on my desktop at work.  Neither of those comes with a builtin USB boot capability.  I knew this when I decided to move to USB boots for installs.  My original plan was to use USB to boot the installer for 64 bit isos, and burn a CD or DVD for the older 32 bit machines.

My hand was forced.  I found out that the DVD reader on the older laptop was failing.  I could insert a CD or DVD, and be able to read it.  But when I then try to boot from it, the BIOS tells me that there is no bootable CD present.  With multiple retries, I can usually get it working.  But failing hardware usually gets worse over time.  I could replace the CD/DVD reader/writer, but this is an old machine not worth the investment.  So I tried to find if there was a way that I could force it to boot from USB.

The first attempt was a grub menu entry.  That failed.  That’s when I decided to try PLOP, a freeware boot manager.  And that turned out to do the trick very nicely.

I did not need to install PLOP as a boot manager.  Rather, I could use grub and/or the Windows boot loader to load PLOP when I need it.  That way it takes only a small amount of disk space and no memory, except when I am actually using it.

My first attempt to boot the older laptop (a Toshiba) from USB failed.  I plugged in the USB flash drive, and the light on it lit up.  Then I booted to PLOP via grub.  In the PLOP menu, I selected USB.  And the flash drive light went out – it looked dead.

Fortunately, there was another method with PLOP.  When ready to boot the USB, instead of selecting the USB entry and hitting ENTER, I could instead hit “U” (i.e. SHIFT U).  PLOP then attempts a USB boot in USB 1.1 compatibility mode.  And, fortunately, that worked.  It’s a bit slower than using USB 2 mode, but it gets the job done well enough.  I later tested the same method on my older work desktop, and I was also able to boot that from a USB.

Incidentally, my first test of USB booting was to test and later install opensuse 12.1 Beta1.  I currently have that working on my older laptop, where it is the only linux version installed (along with WinXP).  I also have the 12.1 Beta1 installed as a second linux version on my main laptop.


About Neil Rickert

Retired mathematician and computer scientist who dabbles in cognitive science.

One response to “Booting from a USB”

  1. Neil Rickert says :

    I tried using Plop to boot a USB drive from a relatively new laptop. It told me that no bootable USB was found.
    Looking more carefully, I noticed that it showed two hard drives. Booting the second hard drive turned out to be booting the USB. Apparently the BIOS is recognizing the flash drive as if it were a hard drive rather than a USB device.


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