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Missing MSR partition after disk conversion

I did submit this question to support but will also post it here to see if anyone else has experienced this and might have an answer.

i did a disk conversion from MSR to GPT using Partition Asst Pro. This was my C drive, system disk with my OS (Win 10 home, 64 bit). There was only 1 partition on the drive, the OS partition. The conversion completed okay and the EFI partition was added after the OS partition and the system boots fine using UEFI boot (CSM disabled). Microsoft says there should be an MSR partition for a UEFI boot drive to work properly. So my question is: Why does my system seem to work without it and what problems might occur in the future without that partition? I know it is a hidden partition and I'm not using Disk Management to look for it, but am using Partition Asst Pro (and I also used Diskpart to see if it was there). I guess I could add: Why doesn't PA add that partition also during the conversion?


  • @Flyer, AOMEI Partition Assistant doesn't create MSR partition when converting disk from MBR to GPT. 
    And, the MSR partition doesn't affect the UEFI system boot.
  • Thank you for stating what I already know.

    I know PA didn’t create the MSR partition and I know the disk will boot without it. 

    My question is what are the potential problems that might arise without that partition? 

    “Microsoft expects an MSR to be present on every GPT disk, and recommends it to be created as the disk is initially partitioned.”

    "Microsoft reserves a chunk of disk space using this MSR partition type, to provide an alternative data storage space for such software components which previously may have used hidden sectors on MBR formatted disks. Such software components can create a small software-component specific partition from a portion of the space reserved in the MSR partition.” (These quotes are from Wikipedia)

     I can give you multiple quotes from numerous sources that talk about the MSR partition and why it should be there. Are you aware of any program or Windows function that relies on having the MSR partition available?

  • @Flyer, Generally, the MSR partition is not necessary and can be deleted without being affected. We currently don't know any programs and windows functions that need to use the MSR partition.
  • Thank you. That is the information I needed. PA worked great doing the conversion.
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