Just a little info regarding changing drive letters, specifically, after backing up and cloning your OS drive, to a new drive..

Normally it would not be a problem to pull the cloned old drive out and reboot the computer, so only ONE OS drive installed. Windows would boot up and assign drive letter C: to the new disk...

In cases where you have multiple partitions, or a more complicated setup and you need to retain specific drive letter assignments without removing the old C: drive, windows will not allow you to re-assign drive letter C: to the new cloned disk..

To get around the windows drive letter protection thing, there is a little registry editing involved.

How to change a SYSTEM drive letter in windows xp, when disk management won't allow it..

If you know how to use windows REGEDIT you can do the drive letter swapping yourself.. ; ...
Quote Originally Posted by networktechs XP tweaking guide
Windows XP performance Tweaking Guide

Regedit - Knowing how to use it to edit your registry is a MUST for this guide. It is the only tool that we're using here.

To run it you will have to click on the start menu and select run. From there you type regedit. From there you can browse around and find all kinds of things to change/edit. If you're new to this make sure you look but NOT touch. Make sure that you make a backup before you touch anything. To do this you click on File and then export. Save the registry file someplace safe and if your screw something up you will have to return to regedit and either fix your changes or import the old file. Basically browsing the registry is setup just like browsing folders in windows explorer. You will see the keys within that folder in the right side box. Right Click on them to see what all you can do with them.[editted to fit with this topic]

Now on with how to swap drive letters:

Log into windows XP as the Administrator, go to the start menu, select RUN, type in REGEDIT.EXE, back up the registry using the guide quoted above, then..

Browse to the registry location:


Then find \DosDevices\[drive letter]
Where [drive letter] will be the drive that windows is installed on, or your NEW cloned disks drive letter...

If you installed windows on C: and have done your cloning to your new disk, locate \DosDevices\C: then Right click on \DosDevices\C: then select "rename" from the list. Change the drive letter C: to one that is not currently in use by disk management, typically Z: will work. This is just a temporary drive letter used to free up C: so that you can re-assign C: to another disk.

If you cannot change/rename this registry entry, you may have to select "permissions" and give the administrator temporary "full control" of "MOUNTED_DEVICES" or individual "DosDevices"..

If you have just one other drive, with no other partitions, use disk management to identify the NEW disk and it's CURRENT drive letter, then find the NEW disks current drive letter in HKEY_LOCAL_MACHINE\SYSTEM\MOUNTED_DEVICES, then right click on it and select "rename" Change the new disks current drive letter to C:

If you have multiple partitions, pay close attention to the partition drive letter assignment.

Some multiple disk/multiple partition installations might consist of individual physical disks just for the operating system, applications, games, even a swapfile.. If well planned, the swap file and OS would be on separate individual DISKS, and the GAMES/APPS/DATA partitions would have their own DISK, with different partitions.. This would provide individual controller channels and increase system response/data transfer opperations would take less time than if this was all stored on ONE system disk...

If your OS is on a different drive than your applications and program files, and you wanted to use a cloning or disk imaging application to backup and restore just the opperating system; and keep your application installed files and still be able to use those applications after putting in the new cloned OS disk, you need to only swap the drive letters of the NEW OS disk and the OLD OS disk, and leave the other drive letter assignments alone..

Use Computer Management/Disk Management to make sure your physical disks and their logical drive letters, are the correct disks and letters that you want to swap..