I have a 20G logical volume with 5G of data which I'm backing up as a sparse image, as follows:
dd conv=sparse if=/dev/group/volume of=/mnt/backup/foo.img
This takes about 3 minutes, but restoring it from the same media takes about 25 minutes using this command:
dd if=/mnt/backup/foo.img of=/dev/group/volume
Is there a faster way to do this? Or are there some options I can fine-tune to speed it up? The backup media is formatted as ext4, but this could be changed.