MSR Partition vs. System Reserved Partition RRS feed

  • Question

  • I'm new to Windows Server management, and to these forums as well.  I hope this is an appropriate forum for my questions.  If not, please direct me to the correct forum.

    I have a few questions that I have been unable to get answered with my own research.  I will group subjects as much as possible and probably create a few different posts.

    I have been trying to figure out a few things regarding the partitions that are created when Windows Server 2008 R2 is installed.  Specifically:

    1) I've seen the MSR on a server partitioned using GPT, and the System Reserved partition on a server partitioned using MBR.  Are these partitions the same thing?  Are they somehow different, but perform the same function given the partitioning scheme (GPT vs. MBR)?

    2) I know that the initial size of the MSR can vary depending on the size of the disk. Is there a formula for determining how big the MSR will be on a disk of any given size?

    3) I know that the partition GUID can vary depending on whether GPT or MBR is used.  How can I find the GUID for a partition?

    4) Is it a true statement to say that every GPT disk must contain an MSR, and that therefore any disk containing an MSR was partitioned using GPT?

    Thanks for any help that you can offer!


    Friday, August 17, 2012 6:36 PM

All replies

  • Following articles might help you...

    Understanding Disk Partitions


    What is the Windows Server 2008 R2 / Windows 7 System Reserved Partition?


    Frequently asked questions about the GUID Partitioning Table disk architecture


    Windows and GPT FAQ


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    Friday, August 17, 2012 6:58 PM
  • The first article answered questions 1 and 4.  The MSR is used only on UEFI systems, meaning it is not the same thing as the System Reserved partition (Question 1) and making the statement in question 4 true.

    I had already read the other 3 articles and they don't contain the information that I'm looking for.

    That leaves questions 2 and 3 still unanswered.  With the sizes of today's hard drives, the answer to question 2 will be a bit acedemic.  Just leave a few GB of space on the drive for Windows to do it's thing seems like a good rule of thumb.  But if there is a formula to calculate the initial size of the MSR, or a table where I could look it up, I'd like to know that.

    As for question 3, I really do need to know that because I want to write a PowerShell script to check the partition GUIDs as a way of knowing which servers have been partitioned using UEFI.


    Wednesday, August 22, 2012 1:51 AM
  • http://en.wikipedia.org/wiki/Microsoft_Reserved_Partition:

    "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 . . . . .Initial size of MSR is 32 MB on disks smaller than 16 GB, or 128 MB on other disks, although it may later automatically shrink on behalf of other partitions, for example during the conversion from basic disk to dynamic disk."

    Friday, January 11, 2013 12:57 PM
  • I encountered another little/big problem. I has to do with using windows image backup requiring 50mb free space on partitions 499mb and smaller to create a volume shadow copy. [UEFI- GPT] Windows 8.1 Pro setup creates partition 1 (system reserved/recovery) of 300mb using 265mb leaving only 35mb free :-( Image backup fails. Partition 2 = EFi, Partition 3 = MSR (GPT Reserved) partition 4 = Basic Data (Boot/OS) Ultimately my solution was to delete the MSR (128mb) partition, use partition wizard to slide the EFI partition down then using diskpart to reset ID back to EFI which then allowed me to extend partition 1 to 428mb. Image backup works both on capture and apply. It is my understanding that the MSR partition is required only if you intend to convert the disk from basic to dynamic. Is this true?
    Wednesday, February 12, 2014 5:57 PM