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  1. #1
    5 Star Lounger
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    System disk drive letter

    A friend just had his hard disk go phut, confirmed by the local computer shop. He bought a new drive and installed Windows XP on this; the old disk (from which the computer would not boot) was left in the machine by the computer shop.
    Having copied all the files he wanted from the old disk (it still worked a bit) he removed it from the PC. The PC then refused to boot, so he put it back. The PC nows boots but at some point (he didn't say exactly where) he gets a message saying that the system has found two copies of Windows XP; which one should be used to boot from? He chooses the new disk and the PC boots OK.
    I have established that he has given the new drive a drive letter of G: This means (to me at least) that when the old drive is removed, there is no C: drive.
    Is it a requirement that the system drive has the drive letter C:? I know that the abscence of a C: means some applications will fail but what about the operating system?
    I did find this in the archives so I am wondering if he either has to go into the BIOS to change the HD boot up drive to G: or remove the old drive and rename the new one as C:
    Which is correct/better, please?
    Thanks
    Silverback

  2. #2
    Silver Lounger
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    Re: System disk drive letter

    To make long story short:
    - A computer is booting from the first partition on the first bootable drive (Microsoft called it "system partition".) This is a partition where NTLDR file is, it always get a letter C:
    - Windows starts from partition where Windows folder is (Microsoft called it "boot partition"), its location is written in boot.ini file on system partition. Boot partition can be the same as system partition; if not, it may get letter D:, E:, F: and so on.

    Remember, you cannot change letters for system and boot partitions; to change these letters you must re-install Windows.

    Now answers to your questions. Hard drives on your friends' computer were configured the way that old drive was the first, and new drive was the second (maybe connected as not bootable at all). Then Windows was installed. Windows setup recoginzes previous installation (on drive C , and creates a new installation, giving it next available letter (D:, E: and F: were already used).
    After the installation, boot.ini contains something like this:

    [boot loader]
    timeout=30
    default=multi(0)disk(0)rdisk(0)partition(1)WINDOWS
    [operating systems]
    multi(0)disk(0)rdisk(0)partition(1)WINDOWS="Micros oft Windows XP Professional" /fastdetect
    multi(0)disk(0)rdisk(1)partition(1)WINDOWS="Micros oft Windows XP Professional" /fastdetect

    If you want to tell which Windows installation is which, edit boot.ini (Open System from Control Panel, click Advanced tab, then Settings button under "Startup and Recovery" - the third one - and click Edit button), changing the words inside double quotes, for instance, to "Windows XP - old installation" or whatever you want. Remember: rdisk(0) refers to the first disk - in your case, the old one, and rdisk(1) - to the second (new) disk. Do not change any characters outside double quotes!

    What you can do:

    - Make a new drive the first drive. Some BIOSes allow you to change drive configuration from its configuration screen; otherwise change them physically (changing jumpers to "Master" or "Cable Select" on the new drive and to "Slave" on the old drive.)
    - Boot from Windows XP Setup CD and re-install Windows. I would recommend to make a new installation rather than repairing a previous one. Be careful - do not choose an old Windows installation (on the old drive) in any options! Just note: if you want to install Windows on C: drive, the first drive on the first partition must exist before Windows installation starts. So, if applicable, create the partition during Setup first and choose it for Windows installation next (in other words, do not install Windows on "unpartitioned space".)

    Good luck!

  3. #3
    5 Star Lounger
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    Re: System disk drive letter

    Firstly, my friend and I would like to thank you for your detailed and extremely helpful reply; we have both learnt a lot from it. <img src=/S/thankyou.gif border=0 alt=thankyou width=40 height=15>

    The friend phoned the computer shop and got a different (helpful, this time) assistant. He said the following things.
    1. A machine must have a C: drive to function.
    2. It is not possible to change the drive letter of the disc containing the system partition
    3. Remove the old disk and reinstall XP on the new disk. This will automatically be allocated drive letter C:

    This he did and everything is now working as expected. The old disk is now gone!

    Again, many thanks.
    Silverback

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