I want to make disk image in case if something goes wrong. I found few topics and method about zeroing free space, but people also said that method is not safe for SSD. Then I found other method - [Create A Disk Image Without Enough Free Space](http://dustymabe.com/2012/11/15/create-a-disk-image-without-enough-free-space/), but it is a bit old and I don't know if it works on 14.04 with SSD.  

Can I do that by following that guide? If no, please tell me some other method, thanks.