I will try to narrow down my questions because I realize this topic is super broad.
I'm trying to create a Linux bootable USB disk with persistence for the most recent version of Lubuntu (14.10). I've done this many times in the past. To my recollection, it's been finicky at best, but I've always managed to get it to work.
Creating a bootable disk seems simple enough. I used Universal USB Installer, Linux Live USB Creator, and UNetBootin on Windows and used UNetBootin and the standard Ubuntu Disk Creator on Linux. Despite using a multitude of tools, when I boot to the USB, I get the message:
Missing Operating System.
I can confirm this on multiple computers that I know have a BIOS properly configured to read from the USB. Like I said, I've done this before, so I mildly know what I'm doing.
So this experience creates a lot of questions for me:
What am I doing wrong?
I'm trying to write to a 4GB SanDisk Cruzer which, albeit is ~ 1 year old, should work fine. The disk has been formatted by the respective programs and I also partitioned the USB using a disk utility.
What should I try next?
Are there ways to check the integrity of a bootable USB? Can it be repaired so I don't have to go through the process over again?
Are there boot flags that should be checked? Can I get more verbose output as to why the USB won't boot?
Any suggestions on this topic would be greatly appreciated.