On Monday, April 23, 2012 06:43:12 AM Karanbir Singh wrote: > the drive ordering will not matter as long as the bios isnt mapping the > usb disk as sda and/or trying to inject them into boot ordering FWIW, and for the archives, we have a Dell Precision 690 that does exactly that. I have a Seagate GoFlex 1TB 2.5 inch drive with both USB and FW800 'dongles' that I use for data interchange between a Macbook and the 690. The drive is partitioned GPT (for the booting of Mac OS X on the Macbook as a recovery system), and has four partitions. If I boot the 690 with this particular drive plugged in, it hangs the 690's BIOS boot completely. Removing the USB boot device from the boot order doesn't help. Don't know why, and haven't tried to more thoroughly determine if it's the EFI partition or the boot code for Mac OS X or what. No splash screen comes up, the BIOS just hangs after AHCI enumeration (the last set of interfaces in the machine). The 690 is normally capable of USB boot; I used my CentOS 6.2 install USB key with my self-generated Dual Layer ISO on it to do the initial installation. Again, FWIW and for the archives in case someone sees something similar with USB bootable devices getting in the way of normal boot.