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    Design Netflix: the 60-second story

    Design Netflix

    Press play at 9 pm. The episode is already inside your ISP.

    Netflix knows its catalogue in advance, so the files move overnight. The cloud only makes decisions.

    150

    Tbps of video at the global evening peak

    Assume an hour a day per membership, a 3× evening peak and 4 Mbps a stream. Yet only about 14k plays start a second.

    Where do the bytes come from?

    Bad: Rent a pull-through CDN

    A new episode misses every edge at once, across busy interconnects.

    Good: Own boxes inside ISPs

    Filled overnight from a forecast. Bytes never leave the ISP.

    The files move while you sleep

    A storage appliance fills from 2 AM to 2 PM local time, up to 6.5 TB a night. A whole new season is about 224 GB.

    Mid-episode, the appliance streaming to your TV stops answering.

    The trick

    Your TV already holds three or more ranked URLs. It asks the next for the same byte range; the buffer hides the gap.

    18 PB

    saved by 20% fewer bits on one series

    One series streamed for 50M hours at 4 Mbps. So give every title its own ladder: the compute is a rounding error.

    Losing a region costs capacity, not correctness

    1. Every service on the call path is stateless
    2. Each region uses only local resources
    3. No cross-region calls; replicate data asynchronously
    4. Rehearse it: Chaos Kong evacuates a whole region

    Launch night is a flag, not a deploy

    The episodes reached the ISPs days ago. At launch, a gate opens once copies, rights and time line up. No bytes move.

    Remember

    Decide in an active-active cloud; stream from your own boxes inside ISPs, filled overnight. Each play gets a ranked list of appliances, and every title gets per-shot encoding.