Resizing C: requires "preOS" mode?

I have a brand new Ideapad laptop with 1TB HD (900GB in C, 20GB in a "lenovo drive" though not sure what this is, and roughly 80GB for a recovery drive). I want to resize C: down to about 400GB, then create a new F: drive to save my data at about 500GB. I right click C: in partition manager, then select "create partition". I put in the values, then hit "apply", then it tells me it requires "preOS" mode. I've googled around and heard lots of problems with this mode, such as failing to start up, so I just cancelled the operation for now. Can anyone tell me what this "preOS" mode is, and why it's required? I've searched around this site and nowhere does it mention preOS mode is required for a simple resizing task.

Comments

  • Hello Windylan,


    Welcome to AOMEITECH forum. "Pre-OS" mode means that the program will complete the operation in reboot mode, like a Dos window. When running into this mode there is no any other live application except Partitioin Assistant, then the program can complete the operation safely. You said the "failing to start up", I suppose you mean that after reboot the "Pre-OS" mode does not start up. This error may occur in a few computer circumstance, but it won't prevent your system start up. 


    In your case, the operation (shrink system partition) have to be complete in Pre-OS mode, thus it can lock system partition to ensure the safety and complete the operation.


    If you have any other questions please feel free to let us know.


    Best Regards,

    AOMEI Support Team

  • Morning,

    I have a big problem. Pe-OS has been stoped by battery down. My win 7 64 bit cannot start after this. I did almost all (reparin by cd/dvd, repare disk, ...) Restoring to previus date not possible (it ask me to open system protection).


    What can you do to help me ?


    PS : I speak french the, my englis writing is not good.


  • edited November 2013

    Morning,

    I have a big problem. Pe-OS has been stoped by battery down. My win 7 64 bit cannot start after this. I did almost all (reparin by cd/dvd, repare disk, ...) Restoring to previus date not possible (it ask me to open system protection).


    What can you do to help me ?


    PS : I speak french the, my englis writing is not good.


  • edited November 2013

    Hello winkouni,


    We are so sorry for the problem you encountered. Could you please tell us what partition operation you did and what error message is when you boot the computer? Currently you may use a windows recovery disk tool to copy your data in system partition to another place and you may need to reinstall OS.


    Best Regards,

    AOMEI Support Team

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