The compressed image by Clonezilla can be quite small, but when you intend to restore it, you need a drive of the same size as the source drive of larger.
I like Clonezilla, and I have not tried redobackup. I suggest you try a couple of tools, and use the one you like best. You can even pipe the output of dd to a file compression program and reduce the size of the image, similar to what Clonezilla does, but not as efficiently.
also have a look at redobackup. i find it has a nicer interface than clonezilla and does more or less same thing. problme i had with clonezilla is the options are not really explained when you are doing things and there is no way to go back in menu. so if you change your mind while setting up the backup you need to do it all over agian. i guess if oyu are used to it you will do it right the first time and this is not an issue. but for me when i started it was. took me three times through all menues before it continued.
or slower but ~20% better compressionCode:sudo -s dd if=/dev/sdx bs=4096 | gzip > dd-sdx.img.gz sync exit
where x is the source drive, a for the first one. mkusb can be used to restore safely from a compressed image file dd-sdx.img.gz or dd-sdx.img.xzCode:sudo -s dd if=/dev/sdx bs=4096 | xz > dd-sdx.img.xz sync exit
If you want to be 100% sure, get a new drive of the same size of larger, and test that restoring from the backup really works.
My recommendation: Learn Clonezilla and use it. Test that restoring from the backup really works.