How to prevent Windows from creating additional partitions during installation?

I think it is could be because mbr2gpt is often used on systems with a 100mb system reserved, which it converts to esp.

It cant shrink the 100mb to provide the msr. or it would be less than the 100mb minimum specified for esp.

I do slightly nonstandard partitions. I use one of these configs:

EFI - 260MB
MSR - 128MB
Windows - All remaining space - 2GB
Recovery - 2GB

or

EFI - 260MB
MSR - 128MB
Windows - 350GB (varies with size of disk)
Recovery - 2GB
Data Partition - All remaining space

I use 260GB for the EFI even though this is more than the required amount in order to accommodate for 4K native HDDs. This is because the minimum size of a FAT32 partition on those drives is 260MB so I use that in my scripts to guarantee compatibility with all systems.

Also, MSR is 128 MB to be in line with the latest guidance from Microsoft.

Once again, I use a larger recovery partition to make absolutely sure I don't get short on space since Microsoft seems to keep bumping the size requirement on this partition.

hsehestedt said:

I do slightly nonstandard partitions. I use one of these configs:

EFI - 260MB
MSR - 128MB
Windows - All remaining space - 2GB
Recovery - 2GB

or

EFI - 260MB
MSR - 128MB
Windows - 350GB (varies with size of disk)
Recovery - 2GB
Data Partition - All remaining space

Click to expand...

hsehestedt said:

Once again, I use a larger recovery partition to make absolutely sure I don't get short on space since Microsoft seems to keep bumping the size requirement on this partition.

Click to expand...

2 GB is excessive. I would rate 1 GB as more than adequate.

Before the Black Lotus UEFI exploit, Recovery partition was hardly patched except to fix reported corruption errors. Now because of increased awareness on UEFI security issues, it's getting patched often. Which means you need to leave room for:


The last two factors are the ones where the old guidance of 400-600 MB for Recovery failed the most. From stories I hear from other users, the highwater mark can be around 700-800 MB to finish WinRE patching. So 1 GB is more than enough to future-proof it for now.

Okay, I figured I could take the 30 seconds to test this . If you check the tick box to use the previous version of setup, it WILL install without an MSR partition present.

So, here is my personal opinion on the topic: There must be some reason that Microsoft went through the trouble to specifically check for an MSR partition and deny installation onto a disk without this partition in the new setup. Again, this is only my opinion, but I find it difficult to believe that they would purposely code this change without some intention behind it. What happens if in 26H2 or 27H2 Microsoft gets rid of the old setup? I would rather not run into problems in the future and just use the 128MB of space. 128MB means nothing to me. It's a rounding error in storage calculations.

Maybe this is just preparation for something to come in the future, but it seems to me that circumventing this may just be asking for trouble .

@garlin - I have some good reasons for using 2GB for the recovery partition because I do some customization. Also, I will typically use either a 512GB or 1TB Windows drive and I never even use half of that space, so assigning some additional space is of no consequence to me. This is why I specifically noted that I do it in a "nonstandard" manner.

the previous version of setup, it WILL install without an MSR partition present.

Click to expand...

so I was right post #37

Maybe that is why the more sensible setup is also there.

Click to expand...

SIW2 said:

so I was right post #37

Click to expand...

Absolutely, you were correct about the previous setup and I speculated that this might be the case as well. But, once again, I question why the change in setup is being made by Microsoft. Maybe I'm simply being overly cautious.

But, your point about MBR2GPT makes perfect sense and was something I had not considered, so thanks greatly for that.

I think I've beat this to death already, thanks for indulging me.

Just want to say this has turned out to be a very worthwhile thread because the interesting topic raised by @ceo54 has clearly got some of us thinking (including yours truly).

Marcus Vinicus said:

Just want to say this has turned out to be a very worthwhile thread because the interesting topic raised by @ceo54 has clearly got some of us thinking (including yours truly).

Click to expand...

Amen! I learned a couple of new things, so it was well worth my time, even if I got a bit frustrated until @SIW2 helped me to see the light

I usually do 300mb esp plenty of room for the mucking around in the esp I like to do. I started doing that because it is recommended by diskgenius.