Judging by your title, you want to copy a whole partition to another partition, or to a file in another partition?
dd (Data Dump) should do this:
dd -if=/dev/hda1 -of=/dev/hdb1
dd -if=/dev/hda1 -of=~/hda1.bak
where /dev/hda1 is the partition you're copying from, and /dev/hdb1 or ~/hda1.bak is partition or file, respectively, that you're copying to.
If the source medium has errors, you'll want to see my own thread
, which at the time of writing is just a little further down this very forum.