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Asked: 2026-05-27T20:19:04+00:00

The IOCTL_DISK_GET_DRIVE_GEOMETRY example code of Microsoft gives the expected results for the hard disk.

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The IOCTL_DISK_GET_DRIVE_GEOMETRY example code of Microsoft gives the expected results for the hard disk.

The SD card is drive F: and has no file system. The card was previously written by an 8 bit microcontroller and file system is out of the question. In the windows explorer, the SD card size is displayed correctly as 1886 MB. However when I run the program I get 0.01 GB.

Is the example code correct? I slightly changed the original code, the changed one is here.

Can it be an issue with Mingw? I doubt, it works fine for the hard disk. It is mingw32 gcc 4.6.1 on WinXP SP2. The resulting program is run on Win7. I am using Linux and I have very limited access to native Win7.

How can I figure out the size of the SD card without file system?

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1 Answer

  1. Editorial Team

    As pointed out by Hans Passant, the IOCTL_DISK_GET_LENGTH_INFO should be passed to DeviceIoControl.

    Everything works fine if the CreateFile remarks concerning physical disks and volumes are followed. The resulting code is here.

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