Is it safe to only partially restore a disk image with dd?

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http://unix.stackexchange.com – I have saved my whole hard-disk with dd to an image file. The hard-disk contained some primary partitions formatted with ntfs, swap and ext4. I did it this way: dd if=/dev/sda | ssh user@fastmachine "cat - > diskimage.img" Then I have overwritten the first 5 to 6 GB of my hard-disk for testing purposes with a new system: I created a swap primary partition with 1.5 GB. I created an ext4 primary partition with 4 GB. After testing the test system now I want my old system back. But my local hard-disk is very slow when writing. To save time and energy I want to only restore about 6 GB fro (HowTos)