diskpart clean zeros LBA 0 to LBA 2047

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  1.    #31

    So I am going to assume that Diskpart Clean can still continue to be advised for installation failures without adverse effects based on what you have found here.
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  2. Posts : 7,063
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       #32

    @ignatsatzonic,

    I do not have a more than 2 TB drive that would warrant GPT, but I had done some preliminary exploration of GPT structure with the existing drive.

    The interesting fact is, if the GPT Header or GPT Partition Table gets corrupted, it will be instantly and automatically restored from the backup kept in the last sectors of the HDD and you will never even know that a corruption had occurred.

    It is only if the backups in the last sectors of the HDD get corrupted , by virtue of the fact that those backups will be what will be restored to the initial sectors, that may lead to loss of access to the drive.

    My advice to those who have GPT drives is, do backup all the sectors shown by bootice and if ever you lose access to the drive, restore the backups in the last sectors in the HDD with the backups you had taken with bootice. In most cases that will instantly bring access to the drive or else you will be running around in circles for data recovery from a lost drive.

    A diagram of what goes where is below.

    diskpart clean zeros LBA 0 to LBA 2047-arrow.jpg

    If you have upto 4 Partitions, you will back up LBA 1 and LBA 2 and keep it in safe custody in another drive. If you ever lose access to the drive because of corrupted GPT Header and/or GPT Partition Table, restore the backup of LBA 1 to LBA n (the last sector of your drive) and LBA 2 to LBA n-32. In most cases your drive will be accessible again immediately.
    Last edited by jumanji; 27 Jun 2014 at 22:16.
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  3. Posts : 7,063
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       #33

    gregrocker said:
    So I am going to assume that Diskpart Clean can still continue to be advised for installation failures without adverse effects based on what you have found here.
    As long as I do not know or understand what that installation failure is and how it manifests, I can't give a definitive answer.

    What definitive answer can be given is:

    If the Windows installation is working still, though impaired, and if the Windows start sector is 2048, diskpart clean can be executed safely without any deteriment.

    If the Windows installation is working still, though impaired, and if the Windows start sector is 63, diskpart clean will only aggravate the situation by zeroing the NTFS file system on 63 making the HDD vanish almost to a point of no return as for as data recovery is concerned.

    ( Just in the recent fortnight, we have seen two cases of diskpart clean wiping sector 63 ( one was accidental and one was due to misguidance in some other forum - not SF) and both are under extremely difficult data recovery process by the able Anshad.)

    ( For successful data recovery, a valid intact NTFS (Volume boot record ) is essential. Where it is not there, some sort of data recovery is possible with PhotoRec and like-software where these reconstruct the data from specific file signatures and attributes. If it is a multiple partitioned drive, data in other partitions where NTFS remains intact , the data in those can be successfully recovered and copied with TestDisk.)
    Last edited by jumanji; 27 Jun 2014 at 22:49.
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  4.    #34

    OK jumanji I realize now you aren't clear on they type of installation failure I'm talking about. My bad for not explaining it better.

    When Win7 won't install normally it can be for a number of reasons. In the early days it needed all but one stick of RAM removed, then something was inserted in SP1 that resolved that. The remaining reasons are several but are almost all covered in Overcoming Windows 7 Installation Failures - Windows 7 Help Forums which resolves about 90% of them. The remaining 10% are almost all UEFI problems.

    Of those steps the one which works foremost is the Clean command. You'll notice in the commands we also format an Active partition which also can help.

    I hope this helps.
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  5. Posts : 7,063
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       #35

    OK, greg, thanks for clearing it. I had always been in a dilemma whether you were meaning Windows Installation failure as one arising during the course of its installation, or meaning it in an already existing "Windows installation" failing in someway.

    I also mentioned somewhere that "I am no Windows installation specialist" and it is your forte :) and I am none to advise you on it.

    In any case, since a successful "Windows Installation" :) has not come into existence yet, this 63 /2048 issue does not arise at all and you are free to do anything that will result in a successful Windows install.
    Last edited by jumanji; 28 Jun 2014 at 01:28. Reason: ytpos corrected
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