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I have downloaded a image file of Chromium OS and mounted it into my pen drive (4GB) using Ultra ISO software. It occupied 2GB of my drive. Later I formatted the same in Windows using FAT32 but even then the size left on my pendrive is shown as 2GB.

Another strange thing I observed is that I am getting another file system called "exFAT" while I format which I didn't see any where before.

How can I format my pen drive removing the mounted Image and restoring back the total memory of the pen drive to be 4GB?

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the best i asked the question and resolved the problem is to use HP USB Disk Storage Format Tool Worked at its best...and restored my space :) Thanks all for ur valuable replies – user85261 Jun 10 '11 at 12:46

Assuming you are using WIndows, take the following steps:

  • Go to 'Config Panel' -> 'Administrative Tools' -> 'Computer Management'
  • In this console go to 'Storage' -> 'Disc management'
  • Locate your pendrive and remove all partitions on it by right-clicking them and choosing Remove.
  • After you've done this, right-click the empty space and create a new partition, and format it as FAT or FAT32

You can now use the full capacity of your drive again.

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I'm assuming you're on Windows here.

Right click on USB drive icon. Click 'Format'. (Quick Format is OK).


Here's a guide for formatting a USB drive to NTFS in Windows XP. The same principles apply in other versions of Windows.

NB: exFAT is explained here.

NB: Formatting the USB drive will destroy all data on the USB drive. Make a back-up of any valuable data first (e.g. Chromium OS .iso).

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The OP already told that he formatted the drive. My guess is the software he used to 'Mount' the image has actually created a partition on the USB drive, and has left a part of the drive unassigned. Formatting will not help in this case, you'll have to repartition the drive. – Roald van Doorn Jun 1 '11 at 9:56
The question is a little clearer now it's been edited. I posted my answer a couple of minutes before the edit. That said, I'm still not very clear on what's being asked so I'll leave it to the pros. – boehj Jun 1 '11 at 10:12
I just saw the edited post. Now that I've read the non-edited version, I don't think you deserve that downvote, but I cannot remove it anymore... – Roald van Doorn Jun 1 '11 at 13:27
@Roald: Not a problem. – boehj Jun 1 '11 at 13:38

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