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Will not boot into PreOS mode to finish operations (2)


I have downloaded Disk Partition Assistant to give my OS partition on my SSD more space.

I plan to follow these AOMEI instructions to do so:


the SSD now looks like this:


I now want to resize the D: Games partition and leave about 5GB in the unallocated partion. I also want to move the D: partition to the end , which will put the unallocated partion between the C: and D: partition allowing me to then add the 5GB to the C:

This is what I see when I resize D:


I then drag the D: to the end and resize D: to leave about 5GB unallocated:


I also click Advanced and tick the box to optimize for SSD (is this correct?)

I then press OK and get this window:


However, when I press Proceed I get this message:


I have attempted to shut down any and all programs that may be accessing D: but this window still pops up.

If I press Restart now, the computer reboots but PreOS Mode never initiates.

How do I get Disk Partition Assistant to correctly carry out the pending actions?




  • Hello Subhuman,

    As for the D drive is being used error, I suppose the pagefile is located on D. You can verify it in windows disk management. If so, please first remove pagefile and later you can redo pagefile after you complete partitioning the disk.

    After that, please first defrag your partitions and run chkdsk n: /f (where n replaces drive letter) to fix potential errors. Then try "Extend Partition Wizard" to extend C drive.

    If there are any problems please feel free to let us know. 

    Best Regards,

    AOMEI Support Team

  • edited January 2014

    Thanks!  I didn't realise a pagefile was on D:.

    All good now!

  • Hello!  Sorry to necro-revive this thread.

    It seems had I rememebered to check here again when I wanted to do exactly what I wanted to do here last year, I may not find myself in the trouble I am now in. 

    Anyway, I wanted to do the same thing, resize D and increase C, however I forgot all about this very helpful thread and therefore didnt follow the recommendations here.

    Here is what I did instead:

    When I went to Partition Assistant, I first right clicked on the D: partition and selected RESIZE, which created 1GB unallocated space at the end of the drive.

    I then right clicked D: and slected MOVE and dragged it to the end of the drive so the new 1GB unallocated space was adjacent to C:.

    I finally right clicked C: and selected RESIZE and increased the drive size to absorb the new unallocated space.

    I then exited Partitoin Assistant and on doing so saw the messages about all the changes that have been made needing to be carried out.  I tried to select the option to make the changes without reboot but it told me there were programs opened.  I ended up just selecting the "RESTART NOW" option to make the changes in Pre-OS mode oyou see in the window in my original post.

    However on rebooting, I now get the message that MOOTMGR is missing which I know is quite dire. image

    Is it eveident I did something wrong?  Perhaps I should have made the three changes (resize D, move D, resize C) one at a time rather than expect PA to complete them all during the one reboot? 

    How can I attempt to recover my OS?




  • Subhuman,

    By chance, have you ever used Aomei PE Builder to create a bootable drive with Aomei Partition Assistant?  If so, you'll need that tool.  If not, I'd recommend you do this on another PC, so you can create the tool.  Once you've got it, boot from that device (USB, CD, etc.) then open Aomei Partition Assistant.  There's a partition recovery wizard that will allow you to locate and attempt to repair your partition table if it's damaged and you don't see all of your previous partitions.

    Also, if you do see the C: partition is still present, you could try setting that partition active.  By chance, is there also a partition at the very start of the drive that doesn't have a letter?  Windows 7 and later often create such a partition for Bit Locker and other boot level services.  Make sure, if you see that partition to try setting it active as well.  If you see blank space at the beginning of the drive instead of a partition, it may have been there and been wiped in error.  The partition recovery wizard would hopefully locate it at that point.

  • Hello and thanks for the quick reply!

    I have just come back from booting up with my Win7 DVD and selecting Repair Installation.  It seems to have worked as I have been able to boot back in to my OS.\

    However some very strange things have happened. Not too surprising, but when I checked my C: and D: again in PA the unallocated partion was still to the right of D:.  However when I browsed my drives in My Computer, I noticed that C: didn't show the red/blue horizonatl bar like it normally does and like all the other partions that come up in that view.  It also showed that there was 0 space on C:.

    Anyway, after noticing some other odd stuff, like messages about drives being locked, I decided to reboot untill things returned to normal.

    They did but for some bizzaree reason, somehow some 6GB of free space has miraculaous apepared on my C:!  It hasn't come from D: or the unallocted 1GB space I created from D: (I have since merged that space back to D:).

    Anyway, all seems to be good, and even better than what I had planned on doing.

    Now where did around 6GB of space suddenly come from?  Was it possibly from defragging my C:? 

  • Subhuman,

    Without being able to examine the system, I'll have to guess.  That being said, I imagine that the free space was already there.  It was probably showing 0 bytes free due to an error that was corrected through a subsequent reboot.  Defragging rarely frees up space. 

    What usually happens depends on the file system.  In NTFS, the most common file system used with Windows since XP (or earlier if you refer to the NT line) some small files are actually stored in the file table rather than "out on the disk."  Basically if you have files small enough to fit into each individual cluster used by the file system's file table, then it'll get stored there.  Also, if you have larger files that are spread out over the disk, then they may be condensed to storing their data all within fewer clusters.  That would appear to give more disk space, though it's merely procedural with how the data's stored.  

    You'd still be using the same amount of disk space as before, though you'd have more clusters free which would let you store more file data.  Hope this helps.  There's more information on this available online if you're curious, but it could be confusing if you don't have background information on how it all works.

    Glad your system's running right again!

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