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August 14, 2020

Many Win10 PCs Still Use Old-Fangled Boot Disk Layout

Saw an interesting thread on TenForums this morning. It’s entitled “Anyone able to clarify what these 5 partitions are?” And indeed anybody who’s been working with Windows 10 for any length of time can identify them immediately. Here’s an annotated version of the graphic from that very post:

Many Win10 PCs Still Use Old-Fangled Boot Disk Layout.5-parts

Old-fashioned boot/system disk layouts have one recovery partition at the head and another at the tail.
[Click image for full-sized view.]

Why Do Many Win10 PCs Still Use Old-Fangled Boot Disk Layout?

Short answer: because that’s how the Microsoft Windows installer worked until one of the mid-range builds for 20H1/2004 came out last fall (thanks to the reader whose comment helped me set the record straight: I originallly claimed it was 1909, which was incorrect). And those whose disks are already laid out this way will stay this way unless they do a clean install. Two older Win10.Guru posts explore this topic in some detail. First, there’s Kari’s November 13, 2019 post entitled Thank you, Microsoft – An Important Change in Windows Setup. Second, there’s my own December 2 post entitled New 1909 Disk Layout. What makes the foregoing screen cap a bit weird is that the poster somehow munged his new recovery partition at the right-hand side of the disk layout shown. If you read through the post, you’ll get a tutorial on using the reagentc command to restore and reset the recovery partition appropriately.

Anybody who’s been upgrading Windows 10 since before 1909 emerged in Fall 2019 will probably use the same disk layout shown above. My production PC actually has 6 partitions because it’s on an NVMe SSD that Samsung Magician manages. Consequently, it uses an addition 50-plus GB for “overprovisioning.” (That means spare, empty disk space that can take over for other disk blocks showing signs of impending or actual failure; it appears as the lead-in graphic for this story.) But if you do a clean install of 1909 or later versions, the layout sequence will omit a Recovery partition in spot #1, and Run in this order: EFI-MSR-Win10-WinRE instead. And that’s the way we like it!

[Note] The lead-in graphic for this story comes from the Disk Management (diskmgmt.msc) console in Windows 10. The second image originates from Macrium Reflect. Unlike the Disk Management console it shows the MSR partition in all its glory (DiskMgmt.msc omits it completely). Thanks to CountMike for reminding me of this.

Author: Ed Tittel

Ed Tittel is a 30-plus-year computer industry veteran. He’s a Princeton and multiple University of Texas graduate who’s worked in IT since 1981 when he started his first programming job. Over the past three decades he’s also worked as a manager, technical evangelist, consultant, trainer, and an expert witness. See his professional bio for all the details.

4 Responses “Many Win10 PCs Still Use Old-Fangled Boot Disk Layout”

  1. CountMike
    February 24, 2020 at 22:37

    I have both types. One is clean install of 1909 and another on is fast insider that hails from I don’t know when, 1703 probably. Your picture is fro Macrium Reflect but Disk management shows differently, small, 16.2 MB unformatted partition(MSR) just before C: doesn’t show in DM.

    • February 26, 2020 at 21:08

      Yes, you’re right: the lead-in graphic is from DiskMgmt.msc but the second layout comes from Macrium reflect (I copied it from the original post thread at TenForums). Thanks for pointing that out. Always glad to get your input and comments! –Ed–

  2. Zelanium
    February 25, 2020 at 07:22

    Is the change truly in 1909? This article claims it starts with 20H1, meaning that there’s currently no finished release with the new default layout:

    The replies to https://win10.guru/new-1909-disk-layout/ state the same. So: 1909 or 20H1 (2004)?

    • February 26, 2020 at 21:07

      Thanks for catching that. Apparently, some OEMs (e.g. Lenovo) started doing it that way with 1909. But you are absolutely correct to observe that this won’t take effect as the clean install default until 2004 goes into public release in the next month or three. Thanks again: I’ll amend the story accordingly. –Ed–

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