如何使外接式 USB 硬碟 ( USB HDD ) 也可以開機

( source DIY-COMPUTER REPAIR : How to make a bootable usb hard drive )

Important : Not all USB devices are created equal. By that I mean not all USB flash, pen drives can be made into a bootable device. The best way to create a bootable USB drive is to use a utility that writes the files to the device. You can not do this to an external USB hard drive, external hard drives take the same procedure that a normal hard drive does.

Choice # 1: If you have a computer that you can disconnect the internal hard drive and boot from a cd or floppy here are the steps:
         1) Disconnect the internal hard drive (power or controller cable will do it)
         2) Connect the usb drive to the computer, start the computer with bootable cd (How to create a bootable CD) or floppy (How to create a bootable floppy).
         3) Once the system has booted into DOS, using FDISK partition the hard drive with one partition, make it a small partition, 2 gig max, ensure it is an active partition (How to Format a hard drive)
         4) Restart and format the drive, add the files you want to the C: drive.
         5) TEST the drive!
         6) Reconnect the internal drive

 
Choice # 2: If your system does not allow you to access the USB device with FDISK.
         1) Remove the drive from the external enclosure. 
         2) Disconnect the internal drive in your computer.
         3) Install/Connect the external drive in your computer
         4) Go into BIOS and check for the presence of the external drive.
         5) Start the computer with bootable cd or floppy.
         6) Follow the above instructions on FDISK and Format.
         7) TEST the drive!!
         8) Reverse installation procedures to put the drives back into
             original positions.