I started with user volume and worked down to per-user storage needs, which felt right, but I kept second-guessing my HD video size estimates mid-answer.
Start by clarifying the product scope and assumptions, such as whether the lens records continuously or on-demand, and the target user base. Then estimate the number of users, average recording time per user per day, and video quality to calculate daily storage per user. Finally, multiply by retention period and add redundancy to get total storage capacity.
Pro tip: Frame your answer around key assumptions and show how changes in those assumptions (e.g., user adoption, video quality) impact the storage estimate. This demonstrates product sense and adaptability to ambiguity.
Ask clarifying questions to define recording behavior (continuous vs. event-based), video quality (HD implies 720p or 1080p), sync frequency, and target market. State assumptions explicitly.
Estimate the number of active users (e.g., Google's potential market share) and average recording time per user per day. Consider different user segments (e.g., casual vs. power users).
Determine the storage required for one hour of HD video (e.g., 1-2 GB per hour) and multiply by average daily recording time. Convert to daily storage per user.
Decide on a retention policy (e.g., 30 days, 1 year) and multiply daily storage per user by retention days and number of users. Add redundancy overhead (e.g., 2x for replication).
Validate the estimate against known benchmarks (e.g., YouTube storage) and present a range based on different scenarios (low, medium, high adoption).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.