A required partition on every GUID partition table (GPT) disk. System components can allocate portions of the MSR partition into new partitions for their own use. For example, when you convert a basic GPT disk to dynamic, the system allocates a portion of the MSR partition to be used as the Logical Disk Manager (LDM) metadata partition. The MSR partition varies in size based on the size of the GPT disk. For disks smaller than 16 GB, the MSR partition is 32 MB. For disks larger than 16 GB, the MSR partition is 128 MB. The MSR partition is not visible in Disk Management, and you cannot store data on the MSR partition or delete it.