I am using dd to create an image of my boot partition on Ubuntu 14.04. This is my first time doing this.

In checking the usage on my disk, I used df -h. You will see that my /dev/sda1 partition is 5.8G in size...

bash$ df -h

Filesystem      Size  Used Avail Use% Mounted on

/dev/sda1       220G  5.8G  203G   3% /

none            4.0K     0  4.0K   0% /sys/fs/cgroup

udev            3.9G  4.0K  3.9G   1% /dev

tmpfs           797M  976K  796M   1% /run

none            5.0M     0  5.0M   0% /run/lock

none            3.9G   30M  3.9G   1% /run/shm

none            100M   28K  100M   1% /run/user

/dev/sda5       239G   32K  239G   1% /windows

I tried to create in image and save it in /tmp with the following command:

bash$ sudo dd if=/dev/sda1 of=/tmp/ubuntu.image

It started creating an image in my /tmp dir, but as I checked on its progress, the image kept growing to well over 30G before I cancelled it.

This raises a few questions in my mind:

• Why would the disk image be so large?


• Is it going to equal the size
  of the partition?


• Is there a way to keep the disk image to just the
  size of the actual space used?


• Is there a better tool to use?