Solved Installing Windows 11 on an Unformatted SSD (Partitioning Questions)

I'm installing a fresh copy of Windows 11 on an unformatted 2TB SSD. I've already got my key and have created a bootable Windows 11 USB from Microsoft. I know how to install start to finish. My question is about the best practice for setting up partitions. My intention is to create a partition for Windows 11 and room enough for installed program files. I'll call this the OS partition (Operating System). But I also want to create a few other custom partitions.

First, I'm thinking about 125GB for the OS partition, at most. If you have a good arugment for bigger or smaller then talk me out of it, otherwise I'm going with 125GB.

It's my undrestanding that Windows 11 wants multiple partitions. The EFI Parititon, the MSR partition, and the Recovery partition. The EFI is created in front of the OS partition and the Recovery Partition (unlike earlier versions of Windows) is created after the OS partition. The MSR partition is hidden, but I think it goes in front of the OS and there might even be other MSR partitions created each time you create custom partitions. Not sure. Can't see it.

Method one. Upon installing windows for the first time on the unformatted SSD, I let windows fill the enitre 2TB SSD. It will automatically leave enough space to put in the extra paritions it needs, hidden or otherwise. I let the install finish and when I get to the desktop I run Disk Mangement. Here I will see the EFI before the OS and the Recovery partition after. MSR is in there somewhere, but hidden. Because the whole SSD is formatted, the Recovery will also be on the end (far right) of the fully formatted drive. Next, I shrink the OS parition to 125GB. Then, I will have room to create my custom partitions. This will create a situtation where my custom partitions are between the OS partition and the Recovery partition.

Method two. Upon installing windows for the first time on the unformatted SSD, I choose "new" and format a 125GB and wait. When it's finished I see three partitions have been created. I go on and finish the install process and arrive at the desktop where I open Disk Managment. This time I see the EFI partition, the OS Partition (125GB in size) and then the Recovery Partitoin. Again, the MSR is in there somewhere but hidden. Whatever's left of the SSD shows up as unformatted. From that chunk I create whatever custom partitions I want. This will create a situatoin where my partitions all come after not only the OS partition but also to the right of the Recovery Partition. In the future, at the very least I would not want to try to expand the OS partition because doing so would require cutting into the Recovery partition which is adjacent to it. That's not a problem for me as I would be forever happy to leave the OS at 125GB.

I don't really care how it lays out, but does Windows? It's my understanding that windows requires the Recovery partition be to the right of the OS partition, but does it need to also be adjacent? Is there anything about the order of partitions that would make it more efficent (faster access) to have the Recovery Partition adjacent to the OS partition?

So what's the best practice? Method one or method two? Or does it just not matter so long as the Recovery partition comes after the OS partition?

Bonus Question: When doing a full backup image of the OS partition, is it true to say I should also include the other three partitions as well (EFI, MSR, Recovery)?

PeterOz said:

This explains why it goes after the os.

The recovery partition is typically created at the end of the operating system deployment - Microsoft Q&A

Hi, Can I adjust the recovery partition to the front after partitioning through the official script, I found that the capacity could not be expanded after adding new hard drive.

learn.microsoft.com

I think you will struggle with 125gb.
Once you load the os + programs + the space needed for updates to download and unpack - about 35gb
plus windows always likes to have FREE space to work correctly.
you will start running out of space.
I have a laptop with win 11 and office 2007 and nothing else really and already 67gb is gone.
I would go a minimum 256GB but prefer 512GB.

If your computer can take another drive I would put in a 1TB as the os + programs and use the 2TB for data and backup.
IMO it is worth spending the $35.00 - $100.00 odd dollars to save any hassell latter on.

Yes

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Thanks for the help. Very informative!

Let me see if I understand the conversation you linked.

Keep in mind that your link is just to someone giving an opinion in a Microsoft forum. That said, it states "It is recommended to place this partition immediately after the Windows partition." He then continues, "This allows Windows to modify and recreate the partition later if future updates require a larger recovery image." He then explains it expands the recovery partition by shrinking the OS partition to it's left. I didn't realize Win11 actually changed partition size during updates.

In terms of my question, this would REQUIRE that the Recovery Partition be not only after but adjacent to the OS partition. Otherwise the Recovery Partition could never expand by shrinking the OS partition.

As a result, this would REQUIRE that I use Method Two and to have a large space for the OS partiton. Method One would cause problems the very first time a Windows update required expanding the Recovery partition.

Bu then he states, "However, this layout makes it more difficult for end users to remove the data partition and merge the space with the Windows partition. To do so, the Windows RE partition must be moved to the end of the unused space reclaimed from the data partition, so that the Windows partition can be extended."

I think what he's saying here is that there might be a problem if at some later date the OS partition + Recovery Partition turned out to be too small becuase then it couldn't expand. But in this case you'd be in trouble regardless of whether or not you had custom partitions to the right of the Recovery partition unless of course Windows has the unstated ability to expand the Recovery partition TO THE RIGHT, taking from unformatted space instead of shrinking the OS partition to get bigger. So that doesn't make sense to me unless you believe Windows knows to do this when there's no enough room to take anymore from the OS.

Anyway, can you confirm my thinking that Method Two in my OP is the only way to go?

Considering the expanding Recovery Partion, I see why you put so much emphasis on a larger OS partition.

That said, I can't imagine how you could justify a 256GB space for WIndows 11, let alone 512GB, unless you are keeping all your personal data and gaming and video on that drive in which case why are you even making a separate partitions? I don't know Windows 11, but I've been using Windows 10 since it came out and if you account for it and all my 3rd party apps in the "program files" folder, it's never gone above 40GB. How you taking "os + programs + the space needed for updates to download and unpack - about 35gb," then adding M$ Office (and perhaps other 3rd party apps?) and getting 67GB? I have M$ Office 2007, but have only installed Excel and Word. It's about 1/2 GB. If I'm understanding you and the article you linked, the size of the Window OS itself refers more to the 35GB. I don't see why you would expect the other 3rd party apps would significantly expand in the future. So that 35GB core OS would need to expand 8 TIMES to get you to 256GB, or 14 times to get you to 512GB. Seems very unlikely Win11 would grow that much and if it did wouldn't Microsoft warn end users?

If you aren't actually saying you expect that kind of exponential growth of Windows 11 over time, then I must be missing something about your logic or else I'm making wrong assumptions. In that case, please correct my misunderstanding!


A whole other can of worms I thought about last night is the MSR partition which I really don't properly understand. I'm not sure how it works but, based on my experience with Windows 10, it seems to start at 16mb for the Windows partition and then expand with each custom partition added by about 16MB. The problem is, it seems to create only one partition to store this data for the OS partition AND for all other custom created partitions. If this is so, how can anyone possibly create a reliable backup image of just the OS partition without simultaneously backing up each and every custom partition at the same time?

What I mean is, say I backup only the OS partitions +EFI +Recovery +MSR. No problem. Time goes by and of course there are changes to the OS and custom partitions, but then say my Win11 registtry gets corrupted and I want to restore the image for the OS partition only. I'd be restoring not just the OS, but also the EFI, Recovery, and MSR partitions as well. If I'm right that there's only one MSR partititon for everything, doesn't that mean that I might lose data from my custom partitions when their portion of the MSR gets set back to a past version?

In this case, I can really see the case for a separate SSD for my custom partitions only if that would force there to be two MSR parititions. One for the OS on the first SSD and one for all the custom partitions on the second SSD.

Or it's very possible I just have got everything wrong about the MSR partition! I really don't understand what it's storing or why it often shows up at 100% full. Please set me straight if you can.

PeterOz said:

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Follow up. Sorry, way way past the opportunity to edit the above.

Upon further research I'm pretty certain my observations about the MSR partition being expanded based on other custom created partitions is just wrong. Weird coincidence of having 8 partitions when trying to understand what MSR was doing. Sorry for the Goose Chase.

I just installed Window 11 today, custom designating my partition size for the OS. By the time I got to the desktop windows had created the EFI, MSR, OS partition, and Recovery Partition, in that order. (i.e. Method two install) I was able to view the the MSR drive using diskpart.

MSR shows up as 16mb and apparently it can swell to 128mb (or more??) from what I've read about it. My guess is that when Windows needs to make it bigger, it takes it by shrinking the OS partition much in the same way it shrinks the OS partition to make the Recovery partition bigger. Can you confirm? That's my guess anyway. It's got to get it from somewhere and there's just no place else to take from.

On my fresh install I added a custom partition of 100GB. I ran diskpart again and MSR remained at 16mb. So, I guess it's fair to say MSR has absolutely nothing to do with custom created partitions? This is a question I'd like you to directly answer if you can. In this case I have nothing to worry about regarding making backup images of the OS partition and restoring the OS partition so long as I include the other three (EFI, Recovery, MSR).

AND, I'm strongly considering your suggestion of just getting another SSD exclusively for the OS, but I'm still unconvinced of what size I should get so I'm eager to hear your answer to my arguments against such a large allotment of GB for the OS.

FYI: At this point I'm just experimenting with installing windows and very able to go back and change things even to the point of going back and reformatting the whole drive if necessary.

Thanks again, I've really learned a lot from your post!

phillpower2 said:

250GB should be the minimum size drive or partition for Windows, this not only because of the space required for file swapping etc but also space needs to be available for the many Windows and Windows Defender updates that will be coming down the line + Windows itself will keep on morphing from one version to another, from W10 to W11 and whatever comes after that, in essence Windows is just going to keep on growing and growing.

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For reasons I stated above, I still don't see why you'd need it to be that big. Windows Defender on my Windows 10 is less than 6GB.

But, I won't fight ya on it. Why overthink it? At this point I'm already shopping for a good m.2, hopefully with a DRAM cache. If the price and specs are right I could go as high as 1TB. Whatever it is, I'll end up using it exclusively for Win 11 and it's sibling partitions as PeterOz suggested above. I'll save my current 2TB drive non-OS stuff.

When I do a backup image, I never use sector-to-sector (Cloning?) so it's not copying the empty spaces. By this reasoning, an SSD that's bigger than it needs to be really shouldn't take any longer to backup that one that's smaller.

phillpower2 said:

Regarding partitions, as an example only, on a blank 1TB drive I create a 250GB partition to install Windows and the system drivers to, as part of the process Windows creates its own partitions in its own order, there is no reason to want or need to interfere with this process, the rest of the space I partition as required, docs, games, photos etc.

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Right, I agree. That's what I've been calling Method 2. You'd be surprised the number of "guides" I've seen that recommend installing windows to the whole drive and going back later shrink which ends up squeezing the custom partitions between the OS and Recovery partition.

phillpower2 said:

Keep it uncomplicated and the task takes no time + is a whole lot easier to make regular back ups.

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Well, that's the idea. I'm doing my homework now so I don't have trouble in the future.

Anyone out there answer my basic questions about that MSR? Can I get a confirmation that it's only for Windows 11 and has nothing to do with custom partitions I create?

phillpower2 said:

I did above.

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Maybe I'm not understanding you, but I don't think you mentioned the MSR (Microsoft Reserved Partition) at all. My question was about whether or not it has anything to do with the non-OS partitions the end user creates. My guess is it does not, but if it does I need to rethink how I do backups.

I totally agree with you that it's best not messing with any of those windows created partitions. All my intentions have been around not getting in their way.

phillpower2 said:

No worries, the partitions that I mentioned that Windows creates are the MSR partitions, one normally FAT32 and the other NTFS.

The MSR will not impact any partitions that the end user creates and that is one of the benefits of being able to just back up the Windows C: partition on a larger capacity storage device/

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Cool, thanks man. I just wanna see if Peter Oz has anything more to say before closing the thread.

Well thanks everyone. I'll use a second SSD just for the OS and when I do a backup, I'll backup the OS and the other 3 partitions Windows created.

Consider my questions answered and my problem solved.

Have a good one.