Last couple of times that I have run either the "dd" or "dd full disk" command on my server it has proceded to backup the entire capacity of my System Disk. (I'm not sure, but it may have something to do with how the disk is partitioned. If the entire disk is one partition then it makes sense to me that both "dd" and "dd full disk" will backup the entire capacity of the disk. OMV Gurus here will know more on this.) Here are the screenshots from my use of "dd" command just now: (It took my system 9 Minutes to backup 32Gb boot Pen drive)
And here is the screen shot of "dd full disk" method: ( It took my system 10 Minutes, and this time it wrote 31Gb as opposed to 29Gb of "dd' Method)
Thanks. If I understand you correct "DD" or "DD full disk" does the same,... so now I wonder why the options (DD and DD full disk).
Some maths:
if 30gb takes 9 mins. then 90gb will take 27 mins. then in my case of a 500gb disk capacity it will take about 5.5 times 27 mins = 148.5 mins = 2 hrs 25.5 min. in theory.
My conclusion will then be... better off getting a smaller OMV OS boot disk capacity