A local company last year gave away some USB sticks with their products on them in a PDF file. The PDF is now outdated (2010 version) and I find it a waste to throw away a perfectly good USB stick for that.

The problem with it is that the stick is shown as two drives. When I load a partition manager (the free one from Easeus in this case) it displays them as two separate disks. 156 MB and 814 MB.

I cannot see a brand on the stick (they are made in China).

How can I merge them into one disk?


  • What was originally on the drives? You said a document, but which one was it on? What was on the other one? Were they both present when you first inserted the drive or was one hidden? – Synetech Aug 10 '11 at 4:08

First of all I want to say sorry for kicking the dead horse and my English... But since this is the first result when googling for something like "flash drive showsing as two drives" I decided to post the answer...

This is indeed caused by flash drive's firmware, but it's not very difficult to fix it anyway.

This is also the fix for those fake usb flash drives (drives with fake capacity, "256GB" sticks with only 1GB chips in them

  1. Find your device vendor and ID's either by looking on controller chip or using software like ChipGenius (in my case it was Alcor SC908AN)

  2. What you need is MPTool (Mass Production Tool) for your specific controller. Sometimes they are vendor generic, sometimes device specific (it was the second case for me). So google "MPTool ", and you are likely to find some links to manufacturer's download page.

  3. USE MPTools WITH CAUTION! You CAN render the drive useless, so be sure to backup the firmware if it's possible with your tool or be prepared to throw it away if something goes wrong.

  4. Format your drive after firmware is reflashed

I am not responsible in any way for any damage caused by this steps. Hope this guide helps

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If it were just divided into two partitions, you would be able to remove them and create one large partition instead. However in your case, it looks like this stick is specifically designed to identify itself as two separate drives, probably done in harware / the controller. There would be no (easy) way to change that.

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    This is pretty much it - it's specifically in the controller. The only way to do it would be a vendor-specific tool, and since you don't even know the vendor that's pretty much impossible unless you're willing to just experiment and possibly kill it entirely. (It is awfully small and so should be extremely inexpensive, nothwithstanding that you didn't pay for it originally, but still...) – Shinrai Aug 9 '11 at 13:59
  • But what would be the point to making it appear as two drives? I’ve never seen it before (aside from the U3 I mentioned), and cannot think of any practical purpose. Perhaps it’s a bug? – Synetech Aug 10 '11 at 4:04
  • I guess you would need to ask whoever gave you the stick. I guess it is intended for handing out merchandising (free to use USB stick) while also handing out marketing material (on the second "drive") that you would not need to delete to use the rest of the stick (was the PDF material write-protected?). – BennyInc Aug 10 '11 at 8:39
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    Synetech inc.The idea behind it is they give you a free stick but also their products in PDF. The bigger disk is for use by yourself and the small part they use to put their PDF and presentation on. Its like benny said I gues. And yes. The PDF stuff was protected. Deleting it would not work. So I just formatted the whole thing. @Shinrai: I would love to experiment with it. Any suggestions? – Jarco Aug 11 '11 at 13:53
  • @Jarco - Unfortunately, I've never had occasion to try this sort of thing myself, so I can't offer any pratical advice. I just know that it's theoretically possible and I believe there are tools floating around. – Shinrai Aug 11 '11 at 14:01

Do you have stuff on the drive already? If not, you can just delete both partitions and create one that uses the whole disk.

If you do have stuff (and cannot move them elsewhere for a while), then you can use Easeus to do it (you’ll need a new enough version that supports this, eg 9.0).

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  • I deleted both partitions. The usb stick still shows as being 2 separate drives. – Jarco Aug 9 '11 at 7:30
  • Can you post a screenshot? Also, try using the Windows Disk Management console (Start->Run->diskmgmt.msc) – Synetech Aug 9 '11 at 7:32
  • Added screenshot in main post. – Jarco Aug 9 '11 at 7:36
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    Ah okay. I see. Hmm, that is unusual. I have seen something like this with a U3 Sandisk drive which showed up as a small CD drive and a large flash-drive. This one however looks like two flash drives, so I don’t think that’s what’s happening. – Synetech Aug 9 '11 at 7:38
  • What you could try is to use a program like HxD to open the drive at a low-level and fill it from the very first byte, to the very last byte with 0’s. That way it won’t—or at least *shouldn’t*—get interpreted as anything unusual. – Synetech Aug 9 '11 at 7:40

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