While EXT4 may or may not work with CloneZilla / PartedMagic (I have not tested lately, but my last attempt failed miserably), fsarchiver is a very handy little tool for creating an image of this version of the standard Linux filesystem.
fsarchiver is included in (almost) all Linux distributions, and you will definitely find it on live and recovery filesystems, like System Rescue CD or PartedMagic.
Making an image of a partition/filesystem is relatively simple:
fsacrhiver [-v] savefs destination source
For example, to backup the /dev/md0 filesystem to /backup/md0-backup.fs, run
fsarchiver -v -z 5 -j 2 savefs /backup/cnt/md0.fs /dev/md0
where
v = verbose
z = 0…9 (compression level, 0 being max)
j = number of compression threads (equal to the number of CPU cores available)
