How can I create a larger EFI partition during a fresh Windows 11 Pro install

Winuser · Sep 15, 2025

gunrunnerjohn said:
Sure it is, I just fired up MiniTool Partition Manager First I shrunk my Windows partition by 102MB and moved it to the right.

How did you move the 16 MB hidden partition to the left of the 100 MB EFI partition? All of my computers have the hidden partition in between the 100 MB EFI partition and the C: partition. That's why I can't expand the EFI partition if I ever had the need too. The Partition Wizard how-to says to delete the hidden partition but I don't think that's a good idea.

gunrunnerjohn · Sep 15, 2025

Winuser said:
How did you move the 16 MB hidden partition to the left of the 100 MB EFI partition? All of my computers have the hidden partition in between the 100 MB EFI partition and the C: partition. That's why I can't expand the EFI partition if I ever had the need too. The Partition Wizard how-to says to delete the hidden partition but I don't think that's a good idea.

I didn't have to move it, that's where it ended up when I installed Windows. I never faced that scenario.

Since that partition normally shows up when you format the GPT disk, I have no idea how you got it there.

gunrunnerjohn · Sep 15, 2025

FWIW, you can delete the MSR and recreate it if you like. To recreate it, use DISKPART. Here's what Wikipedia has to say.

Also, in looking I see that they think it should actually be after the EFI partition, but that's not where mine is and Windows doesn't seem to mind.

My previous Windows versions were all on MBR partitions and I never had to deal with an MSR and I never saw one before Windows 11 and GPT partitions.

Winuser · Sep 15, 2025

@gunrunnerjohn I just looked up do I need the MBR partition and it looks like it is safe to delete unless one uses Bitlocker.

gunrunnerjohn · Sep 15, 2025

Winuser said:
@gunrunnerjohn I just looked up do I need the MBR partition and it looks like it is safe to delete unless one uses Bitlocker.

Probably true, it was there and tiny, so I left it. In any case, it appears you can recreate it without too much issue if you really need to.

Winuser · Sep 15, 2025

gunrunnerjohn said:
I didn't have to move it, that's where it ended up when I installed Windows. I never faced that scenario. Since that partition normally shows up when you format the GPT disk, I have no idea how you got it there.

I just looked at my other drives in Partition Wizard. Drive D: my data drive is GPT and does not have the MSR partition. It's possible I may have unknowingly deleted it. The original drive that came with my desktop (I have it hidden so there's no drive letter) that is now running the Canary builds has a 256 MB EFI partition and a 128 MB MSR partition. PowerSpec must have set it up that way. The only thing I ever did to the original drive was to upgrade it to the Canary builds.

gunrunnerjohn · Sep 15, 2025

Hard to say, I never saw the MSR partitions on my systems before now, but I never had GPT partitions until I upgraded to WIn11 earlier this year.

gunrunnerjohn · Sep 15, 2025

Winuser said:
I just looked at my other drives in Partition Wizard. Drive D: my data drive is GPT and does not have the MSR partition. I

You can format a drive GPT and not get an MSR partition with many of the 3rd party partitioning packages. If you it with Windows Disk Management, the 16MB MSR partition is automatically generated at the start of the partition.

Winuser · Sep 15, 2025

gunrunnerjohn said:
You can format a drive GPT and not get an MSR partition with many of the 3rd party partitioning packages. If you it with Windows Disk Management, the 16MB MSR partition is automatically generated at the start of the partition.

I did read that if a GPT drive is used as a data drive there is the possibility that a MSR partition could get created at the beginning of the drive even though it's not needed. One thing I do have to admit, by posting my question and doing a little searching I know a lot more about the MSR partition than I did.

gunrunnerjohn · Sep 15, 2025

Winuser said:
One thing I do have to admit, by posting my question and doing a little searching I know a lot more about the MSR partition than I did.

Me too!

Megahertz · Sep 17, 2025

I don't know (on Win 10 & 11) what a MSR partition is used for.
In Win 7 it was used only with Ultimate and bitlocker so I suppose it is used to store a bitlocker key
Maybe on Win 10 & 11 it does the same.
What is known:
- It's only used on GPT drives
- It's not on GPT specifications. It's only a MS specification
- When you convert a Legacy-MBR drive into a UEFI-GPT drive using mbr2gpt.exe, (a MS tool), the EFI partition is created but not a MSR partition. This tell me that a MSR partition isn't required at all.

gunrunnerjohn · Sep 17, 2025

Megahertz said:
- When you convert a Legacy-MBR drive into a UEFI-GPT drive using mbr2gpt.exe, (a MS tool), the EFI partition is created but not a MSR partition. This tell me that a MSR partition isn't required at all.

Microsoft points people to Wikipedia for their description.

Do I really need a Windows 11 Pro MSR Partition on my hard drive?

Here's that Wikipedia page...

Wikipedia Microsoft Reserved Partition

So the answer to the question is still very murky!

garlin · Sep 17, 2025

MSR partitions are primarily created to reserve unassigned disk space, in case you want to convert a basic disk to a dynamic disk.

The MSR shrinks and some space is assigned to a new dynamic disk database partition. Not everyone will use dynamic disks, but making a MSR guarantees you have the option to convert disks.

Can your Windows live without it? Yes. But many folks use the presence of MSR as a quick "sanity check" when looking at someone's disk layout for signs of a problem.

gunrunnerjohn · Sep 17, 2025

garlin said:
MSR partitions are primarily created to reserve unassigned disk space, in case you want to convert a basic disk to a dynamic disk.

The MSR shrinks and some space is assigned to a new dynamic disk database partition. Not everyone will use dynamic disks, but making a MSR guarantees you have the option to convert disks.

Can your Windows live without it? Yes. But many folks use the presence of MSR as a quick "sanity check" when looking at someone's disk layout for signs of a problem.

I saw the comment somewhere about dynamic disks. In any case, I left the 16MB MSR partitions on mine, I didn't figure it would materially affect my total capacity on a 2TB SSD!

Winuser · Sep 17, 2025

garlin said:
MSR partitions are primarily created to reserve unassigned disk space, in case you want to convert a basic disk to a dynamic disk.

The MSR shrinks and some space is assigned to a new dynamic disk database partition. Not everyone will use dynamic disks, but making a MSR guarantees you have the option to convert disks.

Can your Windows live without it? Yes. But many folks use the presence of MSR as a quick "sanity check" when looking at someone's disk layout for signs of a problem.

From what I have found, it's also needed for those that use Bitlocker. IMO, unless someone has a need to expand the EFI partition it's best to leave it alone.

mccmw · Sep 17, 2025

This would be a good topic to add to the "Tutorials" forum/threads. I never needed anything larger than 100MB for EFI until my wife's HP...I couldn't update the BIOS. I had to use two different tools to get a larger EFI without messing things up...in fact the first time something did get corrupted and I had to restore a backup and start again. I tried Minitool and EaseUS and neither would let me set the EFI to the size I wanted it..when you use their "slider" method it somehow messes around with before and after partition space. Fortunately, booting to Gparted allowed me to do two of the three steps. It let me reduce my Windows partition so that unallocated space was in front. Then it let me move the MSR to the right of it so that the EFI had unallocated adjacent space. However, it failed to let me merge the EFI and that allocated space. I had to boot back into Windows and Minitool let me do it. It was a pain and I'm sure there is simpler way to do it...but that is post-installation. In the future I would love to know the step-by-step tutorial on how to do it pre- or during clean installation.

gunrunnerjohn · Sep 17, 2025

Odd, I had no problem at all changing the size of the EFI partition with Minitool, that included shrinking the Windows partition and putting the free space at the start of the Windows partition. Then I enlarged the EFI partition.

How can I create a larger EFI partition during a fresh Windows 11 Pro install

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