Hi,
Thank you for posting to Microsoft community.
The Microsoft Reserved Partition (MSR) is only used on the UEFI systems using GPT partition structure. It is created to reserve a portion of the disk space for possible subsequent usage by the Windows Operating System. This partition does not contain any meaningful data or any user data. However, it is assigned and ideally used for remapping damaged sectors.
Beginning in Windows 10, the ‘Minimum’ size of the MSR is 16 MB. However, the recommended size for an MSR partition is 128 MB. You could check this link for more information on legacy systems and see if it is helpful.
For further information related to this issue, I would recommend you to post your query in TechNet.
Hope it helps.
Aaron Summith
Microsoft Community - Moderator