Podcast hosting

The brief

You host shows for creators. Listeners press play and download big audio files, and creators upload a new episode now and then. The audio is the bill: every episode downloaded costs bandwidth.

Think of a podcast host.

Users, scale and requirements

Who uses it

200 thousand listeners a month

Audience in plain numbers

200,000 people per month

Normal peak

≈ 40 requests per second

Request mix

Stream chunk: 80%; Read: 17%; Write: 2%; Upload: 1%

Speed for 99 of 100 requests

Stream chunk: ≈ 1,500 ms; Read: ≈ 400 ms; Write: ≈ 400 ms; Upload: ≈ 8,000 ms

Successful requests

99.9%

Data safety

No acknowledged write may be lost.

Monthly budget

≈ $7,700

Data at rest

≈ 40 TB

Where users are

North America: 60%; Europe: 30%; Asia Pacific: 10%

Home region

North America

Waiting deadlines

Stream chunk: 900 seconds; Read: 900 seconds; Write: 3,600 seconds; Upload: 3,600 seconds

≈ marks an approximation, just as in the game. Waiting deadlines measure the age of queued work and are separate from interactive response time.

• An average episode is about 50 MB (approx.). The game groups it into 2 MB stream chunks.

Questions that shape the design

How often does an episode change?

Never after it is published. Audio files are the same for everyone, so copies are safe.

Do listeners all arrive at the same time?

Mostly in the morning commute. But a famous guest can send a huge crowd at once.

Are episodes uploaded often?

No. A few thousand a day across all shows. Uploads are few and can take a few seconds.

What matters most to the creator?

That the episode plays, and that the hosting bill leaves them something to keep.

The traffic day

Morning and evening commute peaks. The clock covers 00:00 to 24:00 in the home region. Events add pressure on top of that normal traffic.

1. 07:30 · Flash crowd

   A scheduled launch brings a sudden rush of requests.

   Traffic reaches 10 times the scheduled load; rises over 30 seconds, holds for 900 seconds and eases over 1,800 seconds.

2. 12:00 · Cost blowout

   A crawler hits uncached pages all day, and every pay-per-use part of the bill multiplies.

   Traffic for Read, Search reaches 1.5 times the scheduled load; rises over 600 seconds, holds for 21,600 seconds and eases over 600 seconds. Other request types keep their scheduled load. Billed usage multiplier: 3. Duration: ≈ 21,600 seconds.

What a strong design has to handle

• Where does the money go in a service that sends big files? Think about what you pay per gigabyte sent.
• A very long cache time keeps the CDN bill down, but a creator who replaces an episode must wait or rename the file.
• Collapsing misses means ten thousand people asking for a brand-new episode produce one request to storage, not ten thousand.

Make a prediction, run a full traffic day, then compare the result. The in-game editorial opens after a finished day and includes measured reference designs.

Concepts to practise

• Copies near users
• Where the money goes