Can You Boot From External Hard Disk Drive

External Hard disk drives connectible to the computer through a USB port are now quite popular. Is it possible to boot from them and run the operating system?

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People naturally would love to have the possibility of using the external hard disk as an alternative to the fixed hard disk inside the computer problems like hard drive beeping; they would love to boot the PC directly from the external hard disk drive and start running the Windows operating system and all other application programs from it.

This need is quite natural and obvious. Just in case the PC’s hard disk crashes, who will not be interested in an alternative and quick option of making the PC alive and usable instantly by utilizing the external hard disk available handy? Moreover, if this facility were to be available, the essence of virtually all your computer activity becomes available in the user’s pocket!

But unfortunately, (at the instant of writing this article in December 2008), the stark reality is that external hard disk drives are not proffered as bootable devices by the disk manufacturers. A portable hard drive is at the best a mass storage device where you can store your files (documents, audios, videos, programs, and so on) just like a normal hard disk and they can always be run them from the computer. They are best for backups and the portability ensures that they can be connected to any other PC thereby giving access to all the user’s files.

Portable hard drive manufacturer Western Digital has stated clearly in their website FAQ section: “Western Digital does not provide technical support for booting your computer using an external hard drive. If you intend to make a copy of your boot drive or install your operating system, please use a second internal drive, rather than an external drive.”

Windows Operating Systems Do Not Support Booting From External Hard Disk

Microsoft Win XP or Vista does not at present support booting from external hard disk.

This means that the user cannot install the OS Software into the External hard disk in a straight forward manner. For booting, a Master Boot Record (MBR) is needed. This must be available on the disk drive, and this includes external disk drives.

This facility is not offered by Microsoft, for the simple reason that it has the potential to encourage piracy.

System BIOS Limitations And The Need For Master Boot Record Information

Many System Bios Setup (older versions) in PCs do not have support for using a USB storage device as a secondary booting option. But some of the latest BIOS do have this option.

When a system boots, it is the system BIOS program that runs first. After doing the preliminary checks, it gets ready to load the Operating System; for that, it looks for Master Boot Record (MBR) information inside the computer. This is (normally) available in the C partition of the Internal Hard drive. Just in case the internal Hard disk has failed to run, the BIOS program will look for the next device (like a floppy drive or a CD drive or another internal hard disk drive – depending on how the BIOS has been set up) for MBR.

If the BIOS program can not accept a USB Storage Device (like the external hard disk) or if the external drive can not/ does not store the MBR, it can not function as the booting device. That is a simple reality.

However, booting of Linex Ubuntu operating system from external USB drives seems quite possible and the procedure involved for this purpose is also reportedly is easy and straightforward.

Is There an “Unofficial” Way Out?

Curious IT experts will always look for unofficial channels to circumvent such limitations to find ways of overcoming such challenges. But from the various discussion forums and websites available on the Internet, it looks there is no sure-fire way existing currently to make the external hard disks bootable for Windows.

There are currently some software programs available (examples: Carbon Copy Cloner and SuperDuper) for totally cloning one hard disk’s total contents including Master Boot Record into another, so that the second hard disk can function totally and exactly as the first one, just in case the first one fails.

But such programs do not seem to work successfully on external hard disks.

Another way is to try and use a good old DOS system’s “Format /s” command (which was used earlier in Win 98 /XP to create bootable Floppy disks). Since the old DOS does not support USB drives, this idea too does not work.

Will Booting From External Hard Disk Become A Reality In the Future?

Again, based on the numerous threads, discussions, and projections available in the internet, there does not seem to be any “official” solution to this very potential demand of the PC users in the immediate future.

For those who want to install application programs in an external Hard disk on their PC and run them from the same PC, there should not be a problem.

To conclude, an external hard disk is really a very convenient and useful accessory in securely having all your data files, photos, videos, music, etc both as a regular storage medium of a computer as well as a backup device.

A user can always carry the drive with them and use those files on any other computer. As of now, external and portable hard drives are meant for this purpose only and they are not destined to become bootable devices in the immediate future.