Quick question about erasing MBR

Discussion in 'Acronis Disk Director Suite' started by Artistar, Feb 28, 2008.

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  1. Artistar

    Artistar Registered Member

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    I want to erase (not fix) the MBR (0,0,1) with Acronis Disk Editor, so i want to know what will happen to the non-system partitions after this?

    In short, i want to keep those, wipe both system partitions (Linux and Win) and erase MBR to get a completely clean start.

    Thanx in advance.
     
  2. MudCrab

    MudCrab Imaging Specialist

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    Do you have backups of the partitions you want to keep? It's always a good idea, especially when you're changing the MBR manually or doing wipes.

    An MBR "fix" will rewrite the MBR and save the partition table. If you zero out the MBR manually, you'll need to make sure not to wipe the partition table portion. I'm not an MBR expert, but, from what I've found, the first 446 bytes in the MBR hold the executable code. The rest contains the partition table and the boot record signature. If you clear the entire MBR (all 512 bytes), you'll lose your partitions too.

    There is nothing wrong with using an MBR "fix" to rewrite the MBR. It will replace what was there with standard code. You can use the Acronis MBR utility or the fixmbr command in the Windows Recovery Console.

    In addition, when you install your OS, it will write its code to the MBR and boot sector, effectively undoing your MBR wipe.
     
  3. Artistar

    Artistar Registered Member

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    Well, now i have that 7.8MB unallocated space problem. Here are my partitions:

    C: Vista
    "D": Linux
    D: non-system NTFS
    E: non-system NTFS

    I have no backup of the whole non-system partitions (just important data), but would like to keep them untouched.

    I've booted from Acronis rescue media into and first deleted those first two partitions, and wiped them after that. But now i have TWO unallocated disk spaces. WTF?! Shouldn't they merge when deleted?!

    Next, i decided to explore them with disk editor. The second one is filled with zeros, and the first one too, but on the first one i cannot find MBR. The first line is under the "Absolute sector 1 : Cylinder:0 ; Head:0 ; Sector:2). Isn't MBR under sector 1?

    And i also don't understand how to create logical NTFS partition without getting that 7.8MB of unallocated disk space. When creating primary partition it doesn't show up, but only with logical. It's weird because i 100% sure that 7.8MB of unallocated space never showed up before, and i partition a lot....

    Any idea how to get rid of these annoying behavior?
     
  4. K0LO

    K0LO Registered Member

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    Artistar:

    The MBR is in Absolute Sector 0. In order to see it you have to first click on the disk to select the disk. You probably clicked on a partition, so you can only see back to the beginning of the partition.

    The 7.8 MB unallocated space is something Windows reserves (I forget the exact reason), but it isn't necessary. You can resize one of your partitions to eliminate it.
     
  5. Artistar

    Artistar Registered Member

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    Hm, it can be merged/resized with 2nd partition only but then that newly created second partition can't be merged with the first one. If i try to merge those 7.8MB with the first one it just reboots.... And like i wrote earlier, if both of those partitions are deleted there are two separated unallocated disk spaces with no obvious reason.... :(
     
  6. K0LO

    K0LO Registered Member

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    It would be helpful to see a screen shot of how Disk Director views your disk. From your descriptions, I am having a hard time figuring out which are primary and which are logical. One picture is worth a thousand words...
     
  7. Artistar

    Artistar Registered Member

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    Here it is:

    http://img131.imageshack.us/img131/939/dsc02414zy5.png

    This was the initial situation, but that 7.8MB showed up for the first time just a few days ago during repartitioning.

    This is what happens after deleting those OS partitons:

    http://img255.imageshack.us/img255/3295/dsc02415er3.png

    Why are those two unallocated disk spaces separated?


    Btw, only creating primary partitions doesn't create that annoying 7.8MB of space - it's interesting that logical NTFS, ext3 and linux swap all creates it.

    Also, merging those 7.8MB as a partiton results with a system reboot - always. This is the program's fault and there's no question about it.

    If i delete all of the partitions, wipe the empty space and then fill the whole MBR with zero's would it affect HDD's functionality in any way?
     
  8. K0LO

    K0LO Registered Member

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    Artistar:

    These two posts have explanations for the 7.8 MB of unallocated space:

    https://www.wilderssecurity.com/showthread.php?t=124945
    https://www.wilderssecurity.com/showthread.php?t=62131

    Post #9 in the second reference (above) goes into a fair amount of detail about what Disk Director is doing.

    If I understand your situation, the problem occurs when you attempt to put a logical partition at the beginning of a drive. That's a no-no for Windows but may be OK for other operating systems. In your second screen shot I believe you could create a primary partition out of the unallocated space at the beginning of the drive and then resize it to include both unallocated spaces. Or you could resize the first logical partition to the left to include one or both unallocated spaces, but if you do this you will still have 7.8 MB of unallocated space at the beginning of the drive since you would then have no primary partition(s) at the beginning of the drive.

    By the way, this may be a terminology issue, but "merge" and "resize" have completely different meanings in Disk Director. Resizing will enlarge or shrink a partition whereas merging two partitions will result in the data in one partition being moved into the target partition, followed by a resize. From what you are describing you don't want to merge but rather you want to resize.

    Finally, you certainly can zero the first sector or the entire drive after copying off any data that you want to preserve.
     
  9. Artistar

    Artistar Registered Member

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    Well, i tried a different partition editor do delete those partitions, and it fixed those problems. After this Disk Director shows unallocated space together (82GB), not separated as before, and creating new logical partitions doesn't create 7.8MB of unallocated disk space anymore.... Now everything works as it should, or better, as it used to.

    And of course, thank you very much for your effort and for being so helpful. I appreciate it. :)
     
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