PiShrink

Making backups of your Pi images is essential but restoring them to a new SD card can sometimes be problematic when the image is the same size or larger than the target SD card. You will get the message that the image is too large for the target device when the image won’t fit.  The solution is a simple bash script called pishrink.sh.

The first step is to backup the image that you want to shrink.

Step 1:
Startup the “Win32DiskImager” program, Here’s the opening screen:
Notice you will need to select which drive is your SD card. in this case my SD card is H:\ then click the NAVIGATE icon just next to the H:\ pull down box, this will open a file-explorer window.

Step 2:
Select a folder on your hard-drive where you want to SAVE the image file of your SD card. In my example, i have a folder named “rpi_backups”.
Also type in a filename of the image you’re about to create, and click SAVE to continue to next step.

Step 3:
Confirm the folder/filename are correct, and now you can click the READ button to start reading your SD card into your (about-to-be-created) image file.

Step 4:
Here’s my image file being written, almost complete at 90% .

Step 5:
It will indicate “Read Successful” and  “Done” when the image has finished writing.

Step 6:

The next step is to shrink the image you just backed up.

PiShrink is a bash script that automatically shrink a pi image that will then resize to the max size of the SD card on boot. This will make putting the image back onto the SD card faster and the shrunk images will compress better.

Usage: ./pishrink [-s] imagefile.img [newimagefile.img]

If the -s option is given the script will skip the autoexpanding part of the process. If you specify the newimagefile.img parameter, the script will make a copy of imagefile.img and work off that. You will need enough space to make a full copy of the image to use that option.

Prerequisites

If using Ubuntu, you will likely see an error about e2fsck being out of date and metadata_csum. The simplest fix for this is to use Ubuntu 16.10 and up, as it will save you a lot of hassle in the long run.

Example

[user@localhost PiShrink]$ sudo ./shrink.sh pi.img
e2fsck 1.42.9 (28-Dec-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/loop1: 88262/1929536 files (0.2% non-contiguous), 842728/7717632 blocks
resize2fs 1.42.9 (28-Dec-2013)
resize2fs 1.42.9 (28-Dec-2013)
Resizing the filesystem on /dev/loop1 to 773603 (4k) blocks.
Begin pass 2 (max = 100387)
Relocating blocks             XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 3 (max = 236)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Begin pass 4 (max = 7348)
Updating inode references     XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on /dev/loop1 is now 773603 blocks long.

Shrunk pi.img from 30G to 3.1G

Download pishrink.sh

 

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