It has been determined already in this question that
tar cannot read input from
How else can a
dd output be archived directly possibly without using any compression? The purpose of doing everything in a single task is to avoid to write the
dd output to the target disk twice (once as a raw file and once as an archive), and to avoid to perform two different tasks, which is a waste of time (since the input file must be read and written and the output read, processed and written again), and can be impossible if the target drive is almost full.
I'm planning to do multiple backups of drives, partitions and folders, and I'd like to benefit both from the ease of having everything stored into a single file and from the speed of each backup / potential restore task.