One USB drive boots, the other doesn't...

[Peter Steele]

I have a process with creates bootable USB disks with FreeBSD 7.0. The creation of the USB disks is pretty straightforward. We have a master OS image saved as a tarball, and when we want to create a new USB disk, we simply create a single bootable UFS partition on the target USB drive and then extract and copy the tarball image onto the USB disk. 

We just got a bunch of new 4GB USB disks from a different manufacturer than we had been using and when we try to boot a system with this disk the BIOS reports a "missing operating system" error. Well, the OS is definitely not missing, so I assume that the BIOS can't read the boot info from the USB drive for some reason. Is there a way around this? Surely there must be away to get a bootable OS onto a USB drive, regardless of it's brand.