dd usage

full hard disk copy

dd if=/dev/hdx of=/dev/hdy
dd if=/dev/hdx of=/path/to/image
dd if=/dev/hdx | gzip > /path/to/image.gz


Restore Backup of hard disk copy

dd if=/path/to/image of=/dev/hdx
gzip -dc /path/to/image.gz | dd of=/dev/hdx

MBR backup

dd if=/dev/hdx of=/path/to/image count=1 bs=512


MBR restore

dd if=/path/to/image of=/dev/hdx