I am using ubuntu12.04 and have never taken backup of my system earlier. In fact I do not have enough knowledge of any back-up program but trying to learn the steps following one illustration avilable from net. The problem is I need to use bare metal restore beckup using a program called "Redo". However this craetes a backup of entire system and the image file tends to be huge. Can I guess what will be the size of the back-up file? If I use command du -sh in my home, the result shows 48Gb. I guess this only includes the files in my home. If system files are taken in addition to these, what will be the size? I tried using the same command in root (/) but after waiting for few minutes, there was no final result so I stopped the command. I need to know these since I have only one external hard drive working whose capacity is about 90Gb (and there are some other files already in it). If the back-up size is more than that, I will have to create separate backup (in DVD) for some files in my home and proceed with rest to be saved in the ext HD. But how do I know/guess size of the final backup file to be created by Redo?
In general are sizes of backup files of pdf/audio/executable files larger than/smaller than/comparable to sizes of original files? Or does that depend on the back-up program?