Rename Drive Letter on XP installation

July 18, 2011 at 08:52:24
Specs: Windows XP Pro
After installing XP Pro on a new hard disk, the system disk was named D:

I need to change it back to C: because an application that I use expects the system disk to be C: and cannot be changed.

If I re-install XP Pro the system disk is still named D:

How can I change it to C:


See More: Rename Drive Letter on XP installation

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#1
July 18, 2011 at 09:08:47
"After installing XP Pro on a new hard disk, the system disk was named D:"

What is currently using C: then?


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#2
July 18, 2011 at 09:16:27
Hi Mickliq,

The hard disk was faulty - I replaced it and re-installed XP Pro. The new hard disk is the only one in the PC, but for some reason (maybe a USB connected external disk) after installation, the system disk was named D:

I tried re-installing, but it still shows the system drive as D:

Could I change it by deleting the partition when given the option during installation.

Thanks


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#3
July 18, 2011 at 09:20:26
Disk Manager will not permit you to change the drive letter of the system drive. If this were done it would render the system unbootable.

Are you certain that this is necessary? I once ran a system with Windows on D: for several years with no problems whatsoever. Some older applications will default to C: but this can almost always be changed during install. I never saw otherwise.

Without further information it is not possible to advise you on how to reinstall to the C: drive. Such as what drives you have and what they are used for.


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#4
July 18, 2011 at 10:29:36
I agree with LMillar. I had WindowsXP running on Drive E for a while and no drive C: in the system at all and if drive D: is the system or boot drive, the no, it cannot be changed without a complete clean install.

When an installation programme offers you drive C: it doesn't mean you have to use drive C:. You can normally use any drive you width. Besides, any application that hard codes the system drive as drive C: is to be treated with caution. It should be using the $system$ system variable which in your case will be pointing to drive D: Bad programming!

Stuart


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#5
July 18, 2011 at 12:37:35
In ALL microsoft OS's to date there would be always a C: drive. C drive is the first bootable partition in the boot order or ide chain for older systems.

What you did was put some system files on a partition that is set before the D: drive.

Delete all the partitions and install it correctly. You can not fix it easily. Every registry entry is would have to be edited.

1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.


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#6
July 18, 2011 at 15:24:55
In ALL microsoft OS's to date there would be always a C: drive. C drive is the first bootable partition in the boot

Not true. As I stated earlier, I operated an Windows XP system with no drive C: in sight, it not essential

Since Windows XP drive letters have been allocated and designated completely different than they were previously so that Windows XP can boot from any partition in the boot table. The only restriction is that it must be a primary partition. That's is why you get these strange anomalies crop up from time to time. It is not a problem providing you dont get hung up on drive C: being the first bootable drive which is a throwback to the days of MS-DOS.

During installation Windows will put the system files on the first disk it finds that has space and the boot files the same. In most cases this will be drive C: but it certainly doesn't have to be. If during the installation it finds drive C: is full then the system files will be put on drive D:, E: or whatever is available The boot files, that is the Windows folder , will also be put on first disk it finds with the necessary space..

Once the installation is complete and providing there are no boot or system files on drive C:, it or the partition be safety deleted or the drive renamed so there is no drive C:

Stuart


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#7
July 19, 2011 at 13:48:57
Sorry Steward. You are incorrect. There is some partition even it not named C that holds the boot files.

I have been at this way too long. You simply can not install a windows OS to a drive fully called D:. By MS's own technet pages you will find that to be true.

1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.


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#8
July 19, 2011 at 14:29:18
I am right. I speak form experience, not supposition.

I HAVE used a Windows XP installation with no drive C: in the system at all, regardless of what Microsoft might say.

It is only likely to happen on a re-installation, not when doing a clean install. If drive C: is full the installation WILL use the next available drive to install the system files rather than abort the installation which is the only other option if there is no space on Drive C:

Stuart


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#9
July 19, 2011 at 14:55:16
This is a well known issue. Usual reason is a usb device was allocated c: by install. As Steward states the system drive ie. the one that contains the boot files does NOT have to be c:

Some rules get antiquanted. Boot files must be on c: is one of them that is not true anymore.

Answers are only as good as the information you provide.
How to properly post a question:
Sorry no tech support via PM's


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#10
July 20, 2011 at 01:06:18
Thanks to all for taking the time to post responses to my question.

The problem that I had was a programme I was installing is hard coded to drive C: (not very clever idea) and consequently I had to have the OS on that drive.

When I installed XP on the new hard drive (required because the original failed) it was allocating C: to a 'removeable USB device' even though there was no external device actually connected to the PC.

Anyway, the problem was resolved by re-naming the USB device to Z: using the admin tools and re-installing XP using the option to delete the existing partition during installation. As expected, this resulted in XP being installed on the C: drive.

Thanks to all


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#11
July 20, 2011 at 15:12:57
There was in fact a "C" drive to the bios no matter how one installed it.

Order in Which MS-DOS and Windows Assign Drive Letters has not changed.
(take note it says windows)

http://support.microsoft.com/kb/51978


http://support.microsoft.com/kb/223188
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.


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#12
July 20, 2011 at 15:51:41
So that has the BIOS got to do with it. The BIOS know nothing of drive letters, not a thing. It is all done by Windows, otherwise the sane BIOS would not be able to boot Linux which is also completely ignorant of drive letters. All the BIOS knows about is partition numbers.

When you understand what happens during an installation as opposed to booting to a working system, then you will understand why the system files can end up on a drive other than C: The second article is irrelevant as it deals with drive letters that have changed. We are dealing with drivers letters immediately after an installation before anything has changed. What existed before the installation is irrelevant.

It is different for Windows XP. MS-DOS knows nothing about USB drives. MS-DOS has no built in support of optical drives. It has to load driver separable after the OS has allocated drive letters to the hard disk as the drive were loaded with a path name. The concept of system drives and boot drives doesn't exist with MS-DOS.

Put all these difference together and it is plainly obvious that Windows XP does things differently then MS-DOS, especially during the installation process.

Boot the Windows XP installation disk and it will often allocate drive letters differently than the installed system does. This is something that has caught out a number of people as the have ended up deleting the wrong partition.

Stuart


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#13
July 20, 2011 at 16:06:01
You can change the drive letter assignment of any hard drive partition in Disk Management to any available drive letter C-Z, EXCEPT for the drive letter for the partition Windows is booted from.
Other than that, if a drive letter you want to use is being used, you can change the drive letter of the partition (or the CD drive or removable drive) that is using it to something else to free up the drive letter you want to use .
........

For XP (and 2000), Setup determines the drive letter Windows sees it's Windows installation as being installed on (the partition the full \Windows folder is installed on) according to whether or not Setup detects existing partitions that have already been assigned drive letters when Setup is being run.

If Setup detects NO existing partitions that have already been assigned drive letters when Setup is being run, it assigns C to the partition the Windows installation itself is being installed on.

If Setup DOES detect existing partitions that have already been assigned drive letters when Setup is being run, it assigns the first available drive letter alphabetically that is not already being used to the partition the Windows installation itself is being installed on, NOT C.

You can make Setup assign C to the partition the Windows installation itself is being installed on, if there ARE existing partitions that have already been assigned drive letters, by HIDING them from Setup while Setup is being run.
- if all the other existing partitions are on a different physical hard drive, you disconnect them, or disable them from being detected in the bios Setup, BEFORE you run Setup
- if any existing partitions are on the same physical hard drive, you can use a "partition manipulation" program to HIDE the other existing partitions BEFORE you run Setup.
E.g. the freeware Partition Logic, or Partition Magic if you or someone you know has it, but it's not free. Or, the freeware Easeus Partition Master Home Edition, but the Dos bootable version of it is not free.


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#14
July 20, 2011 at 16:20:20
actually its not the drive letter booted from but the one containing the windows files known as the boot partition [vs the system partition which contains the boot files] that you can not change.

yes you can add partitions before the boot partition but must hide them from the OS [and this does not always work because the boot.ini uses drive /partition order not drive letters]
You can not take away partitions before the OS partition or this will also mess up the boot via boot.ini and OS registry.

Point here? Plan your partitioning in advance and don't change it later.
Second point? MSDOS drive letter assignment rules don't apply anymore or are loosely applied now with more exceptions to the rule than being a rule.

Case in point: what started this thread. D: contained both the system and boot partition which means it contained the master boot record and boot files as well as the OS files.

Answers are only as good as the information you provide.
How to properly post a question:
Sorry no tech support via PM's


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#15
July 20, 2011 at 16:48:17
How XP's and 2000's Setup determines which drive letter is assigned to the partition Windows itself is installed on can also depend on how and where the hard drive is connected to the mboard, and if it's IDE, the drive's jumper setting.

E.g. I recently installed XP Pro from scratch on a friend's computer.
The hard drive and CD drive were on the same IDE data cable, on the Primary IDE header.
The desktop case has a memory card reader that was previously assigned 4 drive letters in Windows, which is connected to one USB port connection on a USB data header.
I booted the computer from the CD, deleted all existing partitions on the hard drive and made one new one before I ran Setup.

After Setup was finished...

C, D, E, F - the card reader
G - the CD drive
H - the partition on the hard drive Windows itself had been installed on

I found the CD drive jumpering was set to Master, the hard drive to Slave.


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#16
July 20, 2011 at 18:16:49
Last time I checked bios order has a lot to do with drive letters. Modern bios settings can now change how the OS finds how MS selected as the way to designate "C" drive.

The following occurs at startup:

Regardless of whether a second floppy disk drive is present, MS-DOS then assigns the drive letter C to the primary MS-DOS partition on the first physical hard disk, and then goes on to check for a second hard disk.
If a second physical hard disk is found, and a primary partition exists on the second physical drive, the primary MS-DOS partition on the second physical hard drive is assigned the letter D. MS-DOS version 5.0, which supports up to eight physical drives, will continue to search for more physical hard disk drives at this point. For example, if a third physical hard disk is found, and a primary partition exists on the third physical drive, the primary MS-DOS partition on the third physical hard drive is assigned the letter E.

Nothing has changed with how Windows assigns drive letters with one exception of the newer bios settings that allow one to select the first boot drive. It used to be selected by jumpers or channel order. Bios does affect drive letters.

1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.


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#17
July 21, 2011 at 03:52:36
You attribute far to much to the BIOS. The BIOS does not determine how the OS finds the OS or how it designates drive C: The only way that the BIOS may appear to be effecting the letter allocation is the way the OS is loaded from the boot loader. The boot loader is part of the MBR, the very first item the BIOS read from the hard dsik, The Boot loader is put there by the OS during installation.

All the BIOS knows how to do is to load and execute the block of code that is stored at sector offset xx in the first sector of the first track on the designated drive. The code looks at the rest of the MBR which will tell it which partition to boot from. It will then load the volume boot record from that partition which will give all the information it needs to boot the OS, including the location of ntdetect.com, boot.ini and ntldr wich is always in the root folder. Once those files have been located and loaded, you are well on your way to booting the OS..

This installation process conforms to the MS-DOS standard when allocating drive letters as it does not have access to the registry nor to it know anything about system drives and boot drive until they are created during the installation process.. On my system the system and boot drive is drive C: but the installation allocates it D: because it is on the primary slave drive. There was no primary master at the time of installation but there is now. If it were present during the installation but was unavailable because it was either full or it is a USB drive which the installation will ignore it, but it will still have a drive letter..

Letters allocated to these drives during the installation process are kept so you can see why the system drive could end up as something other than Drive c:

Imagine a situation where you are installing to a completely clean hard disk, no partition att all. You boot from the installation disk but have left as USB drive plugged in. As this is the only usable drive in the system it will get allocated C:

At what stage does this change as the installation will not put system drives on a USB drive and drives letters allocated to the system and boot drives at boot time are kept.

It doesn't. The system and boot drives will get allocated drive D: and will remain drive D:

The only time the installation will take note of existing drive allocation and the registry is when it is doing a repair install which is a totally different thing altogether than a clean install.

Forget about MS-DOS, there are so many difference between MS-DOS and Windows XP they just as well be on a different planet. About the only thing that Windows has in common with MS-DOS when it comes to drive allocation is that floppy drives are still allocated A or B.

Stuart


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