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Bandwidth calculation in Design a blob store

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#1

We have 5 Million active users, 50 MB of Data Size, and 20 requests per day.
Total bandwidth = 5,000,000,000 MB = 5000000 GB
Bandwidth = 5000000 GB/Total Seconds = 5000000/86400 = 56.44 GB/second
This should be approximately = 56 GB but in the lesson it is 462 GB

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We have 12.5 TB of Data, Bandwidth should be 12.5 TB/86400 = 12800 GB/ 86400 = .144 GB/Sec = 144 MB/Sec

In the article, it is mentioned 1.16 GB/Sec

Can somebody please review it?

Course: Grokking Modern System Design Interview for Engineers & Managers - Learn Interactively
Lesson: https://www.educative.io/courses/grokking-modern-system-design-interview-for-engineers-managers/requirements-of-a-blob-stores-design

#2

Hi Saurabh.

Iā€™m glad you reached out to us. In the calculation mentioned the unit used for bandwidth is Gbps not GB/sec. 12.5 Terabytes are divided by 86400 to get the Gigabits per second and not Gigabytes per sec. You are correct if we convert this to Gigabytes then the answer would be 0.148 GB/sec but in the lesson the unit used is Gbps. Hence the answer is 1.16 Gbps.

Thanks

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