Ask HN: Scale of real-life DDoS attacks?

What was the biggest DDoS attack you have ever encountered? How many gigabits per second? Packets per second? How many unique source IP addresses? How long did it last?

The peak number of real (non-spoofed) source IPs is also very interesting. I wonder whether it is feasible to automatically maintain a blacklist of offending IPs that managed to establish a TCP connection (and are thus real).