I recently installed a "backups" hard drive. Cost about $80. I don't leave the DAW powered on 24x7, so for me, I know the top-level folders where projects and audio exist, so every day or two I just drag those folders over to the backup drive, and (when prompted) select "over-write". It is kind of manual, but I don't work on Sonar every day of the week, so it works for me. Might not be the "best way", but that will probably vary by user anyway.