Quick tip: Shrink 2G to fit on 1.8GB SD Card.

[cyber7]

Hi Guys
Here is a quick tip I posted on my blog: http://aubreykloppers.wordpress.com

Here’s the thing:
You bought a Raspberry Pi, a 2GB SD card and downloaded a 2GB IMG to create your awesome project, just to find the card is too small to write the IMG file to! The reason for this is that you bought a 2GB SD card, but technically it is only about 1.8G in size! (1MB=1024768b, work it out from there!)

Software/Hardware used for this example:

Raspberry Pi
2GB SD Card
RuneAudio (2GB image)
Win32DiskImager
I used a Generic Turnkey Linux OS to shrink the IMG.

Steps (as root):
Enable loopback:

Code: Select all

modprobe loop

Create a 1.8G image:

Code: Select all

dd bs=1M count=1700 if=/dev/zero of=NEW.img

Mount image as /dev/loop0:

Code: Select all

losetup -f --show NEW.img

Unzip 2GB image:

Code: Select all

gunzip RuneAudio_rpi_0.3-beta_20141029_2GB.img.gz

Mount image as /dev/loop1:

Code: Select all

losetup -f --show RuneAudio_rpi_0.3-beta_20141029_2GB.img

Write 2GB image onto 1.8GB image:

Code: Select all

dd if=/dev/loop1 of=/dev/loop0

Check the different sizes:

Code: Select all

fdisk -l /dev/loop1
fdisk -l /dev/loop0

Unmount the images and zip your new image:

Code: Select all

losetup -d /dev/loop0 /dev/loop1
mv NEW.img RuneAudio_rpi_0.3-beta_20141029_1.8GB.img
gzip RuneAudio_rpi_0.3-beta_20141029_1.8GB.img

You now have a 1.8G image fitting on a 2GB SD Card. Neat, hey?

[ACX]

Hey cyber7, thank you for the tip! I'm sure it will be useful to several people.

[bo.vestergaard]

I get the following:

bo@NP550:~/Downloads$ sudo dd if=/dev/loop1 of=/dev/loop0
dd: writing to ‘/dev/loop0’: No space left on device
3891201+0 records in
3891200+0 records out
1992294400 bytes (2.0 GB) copied, 78.4085 s, 25.4 MB/s
bo@NP550:~/Downloads$

Don't know if beta 0.3 is too big to fit on a 2Gb drive. Has anyone tried this?

[ingohz]

IMHO there is no difference between copying the original image to a smaller CF and the method explained by cyber7. The partition table remains the same in NEW.img and the end of part2 points behind the end of the CF. You won't get a clean partition this way.