Windows 10 Version 1703: USB Stick multi partition support

[German]Microsoft has added secretly a new feature to Windows 10 Creators Update: This is the first Windows build that supports multiple partitions on removable media (like USB-Sticks). Here are a few more details what's in and what's not.


Background: What's the problem with multi partition support?

Storage media like hard discs and removable media (USB sticks) are classified into two categories:

  • Hard disks and media with Fixed Media Bit set
  • Removable media (like USB sticks) with Removable Media Bit (RMB) set

The Fixed or Removable Media Bit is set by the firmware of a media controller. Media with Fixed Media Bit set are threated in Windows as hard disks and will be grouped in Windows Explorer within hard disks (see screenshot below).

Medien with Removable Media Bit (RMB) set are threated in Windows as removable devices. Windows has restrictions for removable media – for instance, Windows file system (Windows Explorer) can mount only the first partition on such a device.

It's possible, to create multiple partition on a USB stick using third party tools or Linux or even Windows command line tool diskpart. But (in contradiction to Linux) Windows will show only the first partition in Explorer for instance. All other partitions are ignored. This causes conflicts, if a multi-partition USB stick created under Linux shall be formatted in Windows. Windows formats only the first partition.

A special case are USB 3.0 Sticks for Windows To Go. Since Windows 8 the operating system is installable as a portable version on USB Sticks. This feature is available for Enterprise edition of Windows 8, 8.1 and 10. But it requires USB Sticks specified as Windows To Go capable (the firmware provides a Fixed Media Bit). Such an USB Stick may contain more than one partition, because Windows is using this media like a hard disk. I've discussed this within my blog in several articles – see link list at the articles end.


Multi partition support in Windows 10 Creators Update

At Windows 10 Creators Update release we learned a lot about the childish Paint 3D app or about Windows ink. But Microsoft never mentioned the new multiple partition support in file system for removable media.

The above screenshot shows a removable media with two partitions within Windows disk management. We see the two partitions and also the logical drivers are offered to be opened in Windows Explorer. In Windows versions prior to Version 1703, only the first partition will be recognized in Windows.

I stumbled upon this detail a few hours ago on German sites. But searching the web broughts me to this entry, where someone mentioned the new behavior a few days ago.

But a lousy implementation …

Unfortunately Microsoft's implementation has stopped half way down the road. Well, we have an extension allowing Windows 10 Version 1703 to mount multiple partition on removable media and show the logical volumes within file manager. But the tools required to create such media structures are not updated in a proper way.

You can use the command line tool diskpart (as it was also possible in previous Windows versions) to create multiple partitions on a USB Stick and format the logical drives. But Windows disk management, used by most users, fails to handle this now media in a proper way.

  • If an USB Stick has been partitioned and formatted already, Windows disk management refuses to shrink a volume (the context menu commands are grayed out). It's only possible to delete a volume or format it.
  • I've created two partitions on a USB Stick. But I wasn't able to shrink the first partition in Windows disk management. But it was possible, right click to the last partition and select Shrink volume within context menu. But this worked during my test only with media, created under Windows 10 Version 1703.
  • Wait, there is another curiosity. I re-partitioned an USB-Stick (deleted all existing partitions and  created two new partitions). But I was only able, to format both partitions at FAT or FAT32 via disk management – I missed the NTFS option. After formatting both partitions as FAT32, I was able to reformat the volumes as NTFS using context menu command Format in Windows Explorer.

Overall that's odd, so I will use third party partition tools like Mini Tools partition manager, to create media in a proper manner. Just a last note: If you have created a multi partition USB Stick in Windows 10 Version 1703, this media isn't fully supported on older Windows versions. Only the first partition will be recognized.

Similar articles:
How to create your own Windows 8 To Go Developer Preview
Creating Windows 8 To Go on a 16 GB USB-Stick
Creating Windows To Go from Windows 8/8.1 (Release Preview)
Windows To Go mit Windows 8/8.1 (Release Preview)
Windows To Go – Windows 8 Consumer Preview on the run …

Windows 8 To Go with Dual-Boot
Windows 8: A cure for To Go Workspace Bug

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6 Responses to Windows 10 Version 1703: USB Stick multi partition support

  1. Pingback: Creators Update supports multiple partitions on removable drives – but not very well @ AskWoody

  2. Bai Onzi says:

    It would be nice to be turned off by default. Now is see 3 annoying messages asking me to format the 3 extra partitions on my thumb drive every time I plug it in.

    • freddy says:

      looking for a solution for this. any ideas? never want to format the second partition because it's used for linux live OS.

      • peci1 says:

        Install Ext2Fs and the partitions will mount instead of yelling at you that they're unformatted :) This obviously works only for ext* partitions, no help with btrfs or reiserfs.

  3. evgen says:

    Have the same problem in hybrid (Win + Mac) USB drive with NTFS and hfs+ partitions. It tries to open and format the Mac part (hfs+). Any ideas how to fix it?

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  5. Pingback: Create a Secure-Bootable UEFI USB Drive | MCB Systems

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