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Capacity Estimation

Assume:

  1. DAU = 100 M users
  2. MAU = 2.5 B users

A. Throughput [requests per unit of time]​

Throughput can be further divided into write-throughput and read-throughput.

So, Let's start with what all operations user can perform:

  1. Uploading Content [Write-Operation]
  2. Sreaming Content [Read-Operation]

A.1: Read-Throughput​

Assume every user sees an average of 10 videoes per day.

Total Read operations per day = DAU * 10 = 100 M * 10 = 1 B read-request per day.

A.2 Write-Throughput​

Assume 0.4 of users uploads content everyday.

Total Write operations per day = 0.4% of DAU = 0.4 * 100M/100 = 0.4M write requests per day

B. Storage [Bytes per unit of time]​

Assume Average size of content is 600 Mb.

Average Content-Size = 600 Mb
Total Storage per day  = Write-throughput * Average Content-Size
                        = 0.4M * 600 Mb
                        = 240 M Mb
                        = 240 Tb per day

Storage for 10 years = 240 Tb * 365 * 10
                     = 876000 Tb
                     = 876 Pb

C. Cache-Memory​

Cache Memory is generally 1% of total storage per day

Cache-Memory = 1% of daily Storage = 0.01 * 240 Tb = 2.4Tb per day

D. Network Bandwidth​

D.1: Ingress Traffic​

Traffic coming into the system i.e. write traffic

Ingress = Write per second
        = (Total Writing requests per second) * (Average Content size)
        = (0.4M / 24/ 60/ 60) *  (600 Mb)
        = (4.6 requests/sec) * (600 Mb)
        = 2.7 Gbps

D.2: Egress Traffic​

Traffic going out of the system i.e. read traffic

Egress = read per second
        = (Total read requests per second) * (Average Content size)
        = (1B / 24/ 60/ 60) *  (600 Mb)
        = (11.57 K/sec) * (600 Mb)
        = 6.9 Tbps