Windows 10: MSR Size Curiosity - GPT secondary disks

Recently working on backups on a PC with 5 HDDs in it and noticed that two 640GB GPT disks had 16MB MSR partitions.

I thought that the size of the MSR was determined by the disk size: less than 16GB = 16MB (Windows 10), and greater than 16GB = 128MB.

Both of these disks were deleted to all unallocated, and then changed from MBR to GPT disks, then formatted NTFS in Windows Disk Management.

Shouldn't these MSR be 128MB?




:)

 

No MSR partition after converting from MBR to GPT a while back?

Yes, we will rebuild the whole thing.

Here's the steps:

1. Copy this code and save it in a file called: EFI.txt to an external HD.
   IMPORTANT: The code uses Disk 0 on first line, make sure you use the same disk #, if not, change it.
   select disk 0
   clean
   convert GPT
   create partition primary size=499
   format quick fs=ntfs
   set id=DE94BBA4-06D1-4D40-A16A-BFD50179D6AC override
   gpt attributes=0x8000000000000001
   create partition primary size=99
   format quick fs=FAT32
   set id=C12A7328-F81F-11D2-BA4B-00A0C93EC93B override
   create par MSR size=16
   list par
   exit
2. Download Macrium Rescue disk ISO.: MacRescue.iso - Google Drive
   build a bootable USB, use: Rufus - Create bootable USB drives the easy way
3. Boot up the PC with the USB. NOTE: there are 2 boot up modes: USB-XXX and UEFI-USB-XXX
   Since your Windows is GPT, Must use: UEFI-USB-XXX
4. Make a complete backup image of your current Windows Disk 0 including D: partition to the external HD.
   (Click on image this disk)
   IMPORTANT: Make sure you verify the image
5. Next, Click on the command icon on the bottom left to open the command windows then type:
   diskpart /s Drive:\EFI.txt where Drive is the the drive letter of the external HD.
   This will create the 1st 3 partitions: 500MB Recovery, 100MB EFI System, 16MB MSR
6. Go back to Macrium Windows, click on Backup tab, click on Refresh
7. Next, click on Restore Tab and select the backup image created in step 4
   Select the destination disk (Disk 0)
8. Drag the Cdrive from top row and drop to the empty space next to 16MB MSR, then drag D: and drop next to C:
   Click next->Finish
9. Once restore completed. Click on "Fix Windows Boot problem". Follow the screen to rebuild the BCD.
10. Reboot

You should have: 499 MB Recovery, 99 EFI System, 16MB MSR and C drive + Drive (16MB MSR is hidden from Disk Management)
Here's a screen shot without Drive D since I only have Windows partitions on disk 0




At this point your Windows Recovery Environment is broken, we will fix that next.

If you have any question. Please ask !!!

 

Win 10 1903, DiskPart command 'convert gpt' automatically creates an MSR partition at the beginning of the disk.

Tired of running out of space in the recovery partition and get windows image shadow copy error
0x80780119, I was just trying out the script to prepare the GPT partitions for windows 10 installation, but rather than using WinPE I just used the DiskPart command on a running windows 10 v 1903 or 20H1 and I noticed that using the script suggested
by Microsoft at this link:

UEFI/GPT-based hard drive partitions

I ended up with 2 MSR partitions instead of one. The 1st Reserved partition was created directly after the command 'convert gpt'

This does not happen if the same script is started from the command prompt of the installation media.

I did not see any documentation stating that the command 'convert gpt' was automatically creating an MSR partition and it was just a surprise to see that it behaves differently depending on the environment. I assume that is fine for a GPT disk that only
has data partitions after the MSR, but not good for a windows system disk.

To work around the problem and running the script on a live system I had to add 2 lines right after the "convert gpt"

---

select partition 1

delete partition override

---

and then continue with the rest of the script.

Results sample with a 64GB disk before the workaround:

Disk 7 is now the selected disk.

DISKPART> list partition

Partition ### Type Size Offset

------------- ---------------- ------- -------

Partition 1 Reserved 15 MB 17 KB <-------- Created automatically with command 'convert gpt'

Partition 2 System 100 MB 16 MB

Partition 3 Reserved 16 MB 116 MB

Partition 4 Primary 58 GB 132 MB

Partition 5 Recovery 1000 MB 58 GB

DISKPART>

rem == CreatePartitions-UEFI.txt ==

rem == These commands are used with DiskPart to

rem create four partitions

rem for a UEFI/GPT-based PC.

rem Adjust the partition sizes to fill the drive

rem as necessary. ==

select disk 7

clean

convert gpt

rem added following 2 lines to work around the duplicate MSR

select partition 1

delete partition override

rem == 1. System partition =========================

create partition efi size=100

rem ** NOTE: For Advanced Format 4Kn drives,

rem change this value to size = 260 **

format quick fs=fat32 label="System"

assign letter="S"

rem == 2. Microsoft Reserved (MSR) partition =======

create partition msr size=16

rem == 3. Windows partition ========================

rem == a. Create the Windows partition ==========

create partition primary

rem == b. Create space for the recovery tools ===

rem ** Update this size to match the size of

rem the recovery tools (winre.wim)

rem plus some free space.

shrink minimum=1000

rem == c. Prepare the Windows partition =========

format quick fs=ntfs label="Windows"

assign letter="W"

rem === 4. Recovery tools partition ================

create partition primary

format quick fs=ntfs label="Recovery tools"

assign letter="R"

set id="de94bba4-06d1-4d40-a16a-bfd50179d6ac"

gpt attributes=0x8000000000000001

list volume

exit

Same 64GB disk sample after adding the 2 lines in the script.

Disk 7 is now the selected disk.

DISKPART> list partition

Partition ### Type Size Offset

------------- ---------------- ------- -------

Partition 1 System 100 MB 1024 KB

Partition 2 Reserved 16 MB 101 MB

Partition 3 Primary 58 GB 117 MB

Partition 4 Recovery 1000 MB 58 GB

DISKPART>

Actual windows disks with increased recovery partition to 1000 MB:

DISKPART> select disk 0

Disk 0 is now the selected disk.

DISKPART> list partition

Partition ### Type Size Offset

------------- ---------------- ------- -------

Partition 1 System 260 MB 1024 KB

Partition 2 Reserved 16 MB 261 MB

Partition 3 Primary 475 GB 277 MB

Partition 4 Recovery 1000 MB 475 GB

DISKPART>





--

 

No MSR partition after converting from MBR to GPT a while back?


Some info....

https://msdn.microsoft.com/en-us/lib...aq_what_is_msr

...and in more understandable language...

https://en.wikipedia.org/wiki/Micros...tition#Purpose

Not that I need to know, it's all MBR here