I'm running a GNU/Linux system, but the hard drive is failing, so I want to make a complete disk image to copy it later to a replacement hard drive.
Can I run the dd command from system itself?
dd if=/dev/sda of=/external/disk/sda.dd
Should I rather shutdown the system, boot a LiveCD and do this when the disk is not actively used by a running operating system?
What could possibly go wrong if I don't?