October 24, 2015

Restoring the Full Capacity of an SD Card

During my projects with single board computers with embedded Linux like the Raspberry Pi, the Beaglebone Black, pcDuino or the Cubieboard, often happens when I need to use and reuse SD cards to install Operating Systems into the boards. However, if later you want to use that same card as a normal storage unit, you might be surprised when you find out that a few MB or even GB are missing and worst, a simple formatting just won't fix the problem.
This happens because the card was formatted to be used with a Linux partition and Windows simply doesn't know how to deal with that. Fortunately there's a tool for that.

The tool is called diskpart and it's included in Windows, it allows you to manage disks, partitions, or volumes. To find it just type diskpart on the Start Menu. It requires administrator privileges.
First enter "list disk", this will show you all disks available. Then identify which one is the SD card you want and memorize its disk number. Insert "select disk #" and replace # with the corresponding number. Make sure you have the right number, if you select the wrong disk you'll end up having catastrophic consequences. Now insert "clean" and then "create partition primary".

Here's a resume of the instructions:

 DISKPART> list disk  
 DISKPART> select disk #  
 DISKPART> clean  
 DISKPART> create partition primary  

After this, the card should be fully recognized by Windows and it's ready to be formatted!

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