@kjoslin This happened because your images are being stored on the base partition, rather than their own partition - and you filled up the server with probably an image capture. While we can help you get this going - without taking preventative measures, this problem will simply happen again.
We have some tutorials showing ‘generic’ good practices for setting up FOG and how to do partitioning. Both of these tutorials have videos showing the partitioning:
https://wiki.fogproject.org/wiki/index.php?title=Debian_8
https://wiki.fogproject.org/wiki/index.php?title=CentOS_7
Here also is a tutorial detailing how to migrate from an old server to a new one:
https://wiki.fogproject.org/wiki/index.php?title=Migrate_FOG
Of course, helping you build a new server and migrate is off topic in this thread, so if you wanted help with that please create a new thread with an appropriate title.