abstract:The Microsoft Reserved Partition, or MSR, is a partition on a data storage device that is labelled with Globally Unique Identifier (GUID) equal to E3C9E316-0B5C-4DB8-817D-F92DF00215AE. The containing storage device has to use the new GUID Partition Table (GPT) format, not the traditional master boot record (MBR) partition table format.