Backup
dd if=/dev/sda of=/dev/stdout bs=1M | bzip2 | ssh USERNAME@remotehost "cat - > drive.img.bz2"
Restore
ssh USERNAME@remotehost "cat drive.img.bz2" | bzip2 -dc | dd if=/dev/stdin of=/dev/sda bs=1M
Backup
dd if=/dev/sda of=/dev/stdout bs=1M | bzip2 | ssh USERNAME@remotehost "cat - > drive.img.bz2"
Restore
ssh USERNAME@remotehost "cat drive.img.bz2" | bzip2 -dc | dd if=/dev/stdin of=/dev/sda bs=1M