Getting Disk Size Properly

Question

I am trying to get the physical device size of a connected USB flash drive. I have tried using WMI.

        ManagementObjectSearcher mosDisks = new ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive WHERE Model = '" + cmbHdd.SelectedItem + "'");
        foreach (ManagementObject moDisk in mosDisks.Get())
        {
            lblCapacity.Text = "Capacity: " + moDisk["Size"];
        }

I have tried using imports to get the geometry:

        var geo = new DiskGeometry();
        uint returnedBytes;
        DeviceIoControl(Handle, 0x70000, IntPtr.Zero, 0, ref geo, (uint)Marshal.SizeOf(typeof(DiskGeometry)), out returnedBytes, IntPtr.Zero);
        return geo.DiskSize;

They all do return a value.. but it is not correct.

For example, the above code returns 250056737280. When I dump the entire binary contents to a new file, FileStream.Length returns 250059350015

See how the last option is bigger? That is also the corrrect size I need to get for my code to work as expected. But I cannot dump 250gb of data just to get the full size. So is there another method to get proper size?

Answer 1

You might consider trying IOCTL_DISK_GET_LENGTH_INFO with DevideIoControl.