BOOTING windows xp FROM USB PEN drive...!!!

Hi gurus and dear friends,

I had this question in my mind form last so so many days...

Q1. Can we boot our desktop or laptop computer from USB Pen drive of say 512 MB or 1 GB...?????

Q2. If yes can we use installed programs and applications on hard disk of our desktop or laptop after booting from pen drive...????? Also how do we prepare pen drive so that its bootable...????

Q3. In case of laptop is it possible that through EXTERNAL hard disk (which has SAY windows xp installed meaning thereby that such external hard disk is bootable) connected to laptop via USB port be used to boot laptop instead of laptop's internal hard disk being used for booting...???????

Q4. A computer (be it laptop or desktop) say

a. has two partition C: and D:.
b. Say the OS windows xp is loaded / installed on both partitions.
c. say now that yahoo messenger is installed on c: only...

Now can I access yahoo messenger program if i boot from D:...??????????????

What if C: has data instead of installed yahoo mess prog...IN that case can i access such data on C: if i boot from D:...????????????????????

Please take your time and then reply only if you are sure as I am myself a lot confused about all four questions raised above....so please take your time and then only reply...

I know the above four questions are NOT easy to answer and only a geek would be in the best position to answer this as normal general users like me normally feel lost....

I would really really appreciate a true geek and tech saavy techie to jump in and answer in an understandable simple way to issues raised above...

Thanks as always for your time, patience and effort and its genuinely greatly
appreciated...

Warmest regards

sunando

sunandoghosh (at) rediffmail (dot) com

p.s. if anyone would ike to add anything which i might have missed...you are more than welcome....

some new computers will let you boot thru the usb, but it is usually an external hard drive. a Pen drive wouldn't have enough space to hold the operating system unless of course we are going to use a Win 95 instalation or something. If you want to boot without a hard drive go with knoppix linux or something.

abe harami kahi ke kutte

yeah, several distros of linux will boot from a usb flash drive...

can't see doing xp tho. tooooooo big.

Ok, I have been doing a lot of looking around as I am very interested in doing this myself.

Booting from a usb device definitely can be done as long as the mother board being used supports booting from usb.

Usually, say if you booted ubuntu linux from a live cd or usb device, files on the drives of the computer (main HDD's, other usb devices) can still be accessed easily but some or most programs will have to be re-installed into the drive that is being booted from.

So, for example I had a usb Hdd that was bootable and had windows xp installed on it (it would have to be a big Hdd - no smaller than 7-8 gigs depending on which os). Anyway, say that my mother board supported booting from usb, and i had selected usb as primary boot. If windows was installed correctly, the computer should boot normally.

Depending on how windows (or any operating sys such as linux) was installed and partitioned, the whole usb drive might be solely dedicated to boot, and have no extra space (this is the case with an ubuntu live cd). Or, the drive could be partitioned, with one partition for boot files, and the other for data. This means that you would be able to store data such as music, cookies, programs, on the drive, as well as being able to boot from it.

If you had the partitioned setup, and were running your computer solely from the usb drive, you could still access and of the other drives attached to that computer, providing the were no security restrictions on them. If, your case, with the two drives and yahoo messenger only being installed on one of them, you could easily access the messenger files but it would not work as it is installed to that specific drive - Not the drive that you are booting from. To get it to work, you would just have to install it to the drive that is being booted from.

You can access the data on all of the drives that are connected to the computer no matter which on you boot from. but only programs that are installed to the boot drive will work.

Now, back to getting an OS onto a usb device in the first place.

In your question, you asked if you could use a 512Mb or 1Gb flash drive. This depends on many things such as which operating system you use and how you install it. Generally speaking, you will need AT LEAST 1Gb of space.

For example, If you decide to download the Ubuntu iso file, and burn it too a disk, you will see that it takes up the whole disk, about 700Mb. But, if you decide to install Ubuntu from the disk and onto your primary Hdd, it takes up about 4Gb of space. So, you can either make a flash drive bootable (this is quite complicated) and tranfer the iso file onto it, using 700Mb, or install Ubuntu onto the flash drive (which automatically partitions and makes the drive bootable) and use 4Gb of memory. It all depends.

Personally, i would not use a flash drive of any size as a boot drive as flash drives have limited read and write cycles and much slower I/O speeds. I think that a usb Hdd is a far better alternative and cheaper per Gb or space as well.

I hope this helps and can people please correct me if any of this information is wrong.

Thanks.