Estimate Storage, Bandwidth and Server Needs for a Local Music Streaming Service
Company: Google
Role: Product Manager
Category: Product / Decision Making
Difficulty: medium
Interview Round: Other
Picture a music streaming app that works like Spotify but serves a single local market instead of the whole world. Estimate how large the computing system behind the app needs to be. Choose the measures of size you think matter (for example storage, network bandwidth and number of servers), build each estimate step by step, and label every assumption you make.
```hint Separate what scales with listeners
Some parts of the system grow with the size of the music catalog and barely care how many people use the app; others grow with how many people are listening at the busiest moment. Estimate those drivers separately before combining them.
```
### Clarifying Questions
- What does "local" mean here: one city, one country, or a small group of neighboring countries? That choice sets the potential user base.
- Will the app license a catalog comparable to a global streaming service, or mainly music from the local market?
- Which measure of size matters for the decision behind this question: stored data, peak bandwidth, server count, or monthly running cost?
- Does the app stream audio only, or also podcasts, video and offline downloads?
### What a Strong Answer Covers
- A clear definition of "size" and a breakdown into catalog storage, user and event data, peak streaming bandwidth and request load.
- A funnel from the local population to monthly, daily and peak concurrent listeners, with each assumption labeled and kept to round numbers.
- Correct arithmetic with units carried through, including bits versus bytes and average versus peak load.
- Allowance for replication, multiple audio qualities, caching and growth, followed by a sanity check of the result.
- What the estimate means for a product decision: which assumption moves it most, and whether to run the infrastructure in-house or rely on cloud and content-delivery providers.
### Follow-up Questions
- The app expands to a neighboring market twice the size, with the same catalog. Which numbers in your estimate change and which stay the same?
- How would offline downloads change your storage and peak bandwidth figures?
- Which single assumption is your estimate most sensitive to, and how would you check it before committing a budget?
Overview: A product manager estimation exercise: size the computing infrastructure behind a Spotify-style music streaming app that serves one local market. It tests building a listener funnel, separating catalog storage from peak streaming bandwidth and server load, keeping units straight, and sanity-checking the final numbers.