Windows 10 Version 20H1 brings an important change in Windows Setup

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  1. Kari's Avatar
    Posts : 17,557
    Windows 10 Pro
       #1

    Windows 10 Version 20H1 brings an important change in Windows Setup


    There’s a fundamental flaw in Windows 10 Setup when performing a clean install on a new empty hard disk or SSD. The same is true when wiping the disk empty on a device containing a previous Windows 10 installation and deleting all partitions and performing a clean install.

    The flaw is, Windows Setup positions the small but important 500 MB recovery partition first on the system disk. If and when future feature upgrades need more space to store the recovery environment, the recovery partition cannot expand, and a new recovery partition is created.

    In a clean install, when user lets Windows Setup to partition a GPT hard disk, the important Windows Recovery partition is created first on system disk (yellow highlight in screenshot), followed by EFI, MSR (Microsoft Reserved, not shown in Disk Management), and Windows partitions:

    Windows 10 Version 20H1 brings an important change in Windows Setup-windows-setop-partitioning-1.jpg

    This is against Microsoft's own guidelines for GPT partitioning. Microsoft tells that Recovery partition should always be placed after the Windows system partition, not first on disk, yet this is exactly what Windows Setup does. Screenshot from official Microsoft documentation:

    Windows 10 Version 20H1 brings an important change in Windows Setup-recommended-gpt-partitioning.jpg

    The problem is, when a future feature upgrade needs more space for recovery tools, the partition cannot expand, EFI partition blocking it. Windows Setup has no alternative, it must create a new recovery partition after the Windows system partition, C: drive (blue highlight):

    Windows 10 Version 20H1 brings an important change in Windows Setup-windows-setop-partitioning-2.jpg

    The recovery partition can something no other partition can: it can expand backwards, when placed directly after the Windows partition. It "steals" the space it needs from Windows partition when next feature upgrade again needs to expand recovery partition. Green highlight shows where the recovery partition would expand next time it needs more space:

    Windows 10 Version 20H1 brings an important change in Windows Setup-windows-setop-partitioning-3.jpg

    Currently, up to Windows 10 version 1909, if user lets Windows Setup to partition disk, it looks like this:

    Windows 10 Version 20H1 brings an important change in Windows Setup-current-partitioning.jpg

    Recovery partition first on disk. However, version 20H1 will change this, as Fast Ring Insiders will see when clean installing recent Insider builds. The recovery partition is no longer created when Windows Setup partitions the disk. Windows will be installed first, and only at final stages of setup, recovery partition is created in correct place, directly after the Windows system partition.

    Here's how Fast Ring Insiders will see Windows Setup to partition system disk now:

    Windows 10 Version 20H1 brings an important change in Windows Setup-20h1-partitioning.jpg

    Recovery partition not created yet, it will be created in correct place only at final stages of Windows Setup.

    This is a minor change in Windows Setup, but with a major impact. Finally, Windows Setup will follow the Microsoft's own partitioning guidelines.

    Kari
      My Computer

  2. dalchina's Avatar
    Posts : 31,322
    Win 10 Pro (1903)
       #2

    Thanks Kari - sounds almost too rational to be true... I suppose upgrading to that doesn't actually delete redundant recovery partitions, does it? (Granted, doing so achieves little bar removing confusion...!)
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  3. Kari's Avatar
    Posts : 17,557
    Windows 10 Pro
    Thread Starter
       #3

    dalchina said:
    I suppose upgrading to that doesn't actually delete redundant recovery partitions, does it?
    No, Windows Setup just creates new recovery partitions when it can't expand the current one, leaving older recovery partitions obsolete.

    A typical mistake made by users is to assign too much space for Windows partition, leading to need to shrink it later to be able to create a new partition.

    In screenshot, yellow marks the original recovery partition, which became obsolete when future feature upgrade created a new one, marked blue. After that new recovery partition was created, user decides to shrink C: partition to create a new data partition. If so, next time a feature upgrade needs to expand the new recovery partition, it can't because it can expand backwards only if directly after Windows partition, so again a new recovery partition will be created in space marked green:

    Windows 10 Version 20H1 brings an important change in Windows Setup-windows-setop-partitioning-4.jpg

    It is a bit confusing, but at least 20H1 will make default Windows Setup partitioning to comply with their own guidelines.

    Kari
    Last edited by Kari; 16 Nov 2019 at 14:15. Reason: Some worst typos fixed.
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  4. Kyhi's Avatar
    Posts : 3,614
    Windows 3.1 to Windows 10
       #4

    This is a minor change in Windows Setup, but with a major impact. Finally, Windows Setup will follow the Microsoft's own partitioning guidelines.
    Well, needless to say, it is about time...
    Thanks For the Updated Info Kari..
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  5. AndreTen's Avatar
    Posts : 24,085
    Windows 10 (Pro and Insider Pro)
       #5

    Thanks for the info Kari.
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  6. Posts : 45
    Win10
       #6

    Build 19025 made 596 MB Recovery partition with 82 MB free space instead of fitting files into old 529 MB partition.
      My Computers


  7. Posts : 45
    Win10
       #7

    Build 19030 made 478 MB Recovery partition with 83 MB free space - clean install into empty drive.
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  8. DooGie's Avatar
    Posts : 9,573
    Wndows 10 Pro x64 dev channel
       #8

    Thanks Kari, useful information there.
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  9. cereberus's Avatar
    Posts : 12,123
    Windows10
       #9

    I agree, this was always annoying, as recovering the 500 MB at beginning on UEFI installs was a real PITA even with tools like Minitool Partition Wizard because even that would not move the 16 MB MSR partition.

    In fact, I have never seen a case where the MSR partition has ever been of any use, even on encrypted installations.

    I almost believe this is a global "in joke" by MS and you just have to work out the MSR partition is a complete waste of space (literally).
    Last edited by cereberus; 26 Nov 2019 at 16:26.
      My Computer

  10. D4ni3l's Avatar
    Posts : 309
    Microsoft Windows 10 x64
       #10

    Code:
    DISKPART> 
    
    select disk 0
    
    detail disk
    
    Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
      ----------  ---  -----------  -----  ----------  -------  ---------  --------
      Volume 0     C   SS-ROOT      NTFS   Partition    218 GB  Healthy    Boot
      Volume 1         Recovery     NTFS   Partition   1024 MB  Healthy
      Volume 2         SYSTEM       FAT32  Partition    200 MB  Healthy    System
    
    list part
    
      Partition ###  Type              Size     Offset
      -------------  ----------------  -------  -------
      Partition 1    System             200 MB  1024 KB
      Partition 2    Reserved            32 MB   201 MB
      Partition 3    Primary            218 GB   233 MB
      Partition 4    Recovery          1024 MB   218 GB
    This what I have (Windows 1909). Is it correct ?
      My Computer


 
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