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.