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Out of the box, Windows will not allow you to partition a USB Thumb / Flash Drive. How can you do this?

In case anyone is wondering Why you would do this?

It's interesting in the case of a BitLocker ToGo drive where you can take a large thumbdrive (like 4 or 8 GB) and format a small amount of the drive to be used normally as a Fat32 drive and leave the remaining partition encrypted using BitLocker. This allows you to keep some non secret data on the unencrypted partition(like portable apps).

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Use a Linux box to create the partition table. :) – Eddie May 4 '09 at 15:38
Or a mac (I think) – Chopper3 May 4 '09 at 15:39
In the future, you should specify OS for this kind of question – Diablomarcus Dec 5 '09 at 6:05
The fact he is asking about bitlocker tells me that its windows. – Saint Gerbil Oct 21 '13 at 9:36
@OmarShahine : I have a first partitions in NTFS and a second one in ext4. MAIN Problem : windows only see the ext4 partition! – user2284570 Sep 10 '14 at 23:15

7 Answers 7

Out of the box, Windows Vista/7 allows the partition of an USB drive. The command is diskpart.

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Answering your own questions is encouraged. It helps create a complete database of solutions here. – Brent May 4 '09 at 15:58
You can't partition a USB drive that's marked as removable, it requires removing the removable bit first. diskpart won't partition a removable drive such as most USB thumb drives, hence my question – Omar Shahine May 4 '09 at 17:14
I am not sure what Windows version you are using, but I have no problems using diskpart on Windows Vista/7 to partitioning flash drives (diskpart, select drive, clean, create partition primary, select partition #, active, format, assign, exit) – user4553 May 4 '09 at 18:53
Check here for more info, it really worked for me: – TrudleR Sep 12 at 16:40

Just use your favourite partitioning tool - Either Disk Management on Windows, or Gparted on *nix, or other - They should all understand USB flash drives, and you simply partition as if it was any other hard drive.

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Disk Management on Windows 7 doesn't seem to repartition, though diskpart as mentioned in another answer does. – paulmorriss Mar 8 '13 at 9:21
The Windows disk management tool disables these features for removable flash drives. – Michael Steele Aug 23 '13 at 22:08
This is wrong! Linux does not have this limitation, but Windows will only be able to see the first partition. – antonio Aug 7 '14 at 23:19
downvoted: information is wrong in case of windows. windows disk management ui does not let you change partitions on a usb flash drive. (it does show them, you can delete a partition, but cannot create a new one, or extend/shrink/etc) – Tuncay Göncüoğlu Oct 8 '14 at 10:43

You can use Windows cmd.exe: run it as administrator and use console utility diskpart.exe to partition the drive. Manual:

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I am coming from a linux perspective, so I would just use cfdisk or if you like a gui, gparted.

You could keep a live CD such as Ubuntu handy for doing these sort of things. Just boot from the CD, do what you have to do, reboot to windows. (it's also great as an emergency rescue solution)

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Windows must be able to recognize the flash drive as a "fixed disk."

This is accomplished by either flipping the removable bit (which doesn't always work), or modifying the cfadisk.c, and .inf files, assuming you're on XP. (You must know how to code for the latter.)

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The problem

Contrary to Linux, Windows cannot partition or properly use a partitioned UFD; that is, if you plug a partitioned UFD, only the first partition will be visible.

The solution

The solution should address two problems: partitioning and make partitions visible. As for the first, an option is to use Linux, perhaps a live distro specifically targeted to imaging and partitioning, like Clonezilla. There are also free Windows tools like Bootice.

The second task is to make all (not only the first one) usable in Windows. A discouraged option is to use tools flipping the removable media bit, as they can damage incompatible sticks.

A better way is to install a filter. A program similar to a drive, adding extra functionality to them. In our case making an UFD appear as fixed drive. See for example Karyonix diskmod.sys discussed on

Side effects and alternative uses

Since Windows can see only the first UFD partition without a filter, one can make some Linux files invisible to a Windows user, by storing them on a partition other than the first.

A special case is a pen Linux distro. If you want to use the pen for storing documents too and you don't want in Windows to make Linux OS files visible, simply do not install the Linux on the first partition.

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One way to do this is using a tool called BootIt. this tool removed the removable bit on the thumb / flash drive and allows you to partition the drive.

I'm sure there are better ways to do this, but this is the only one I can think of.

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