A . Back of the envelope capculations
use round of values. --power of 2 or power of 10
1 million - 10^ 6 1 billion - 10^ 9 1 trillion - 10 ^ 12
1 B- 8 b 1 kB - 1024 B 1 mB - 1024 kB 1 gB - 1024 mB
1 million/day -12 /sec || 700 /min || 4200 /hr
https://dev.to/ievolved/how-i-calculate-capacity-for-systems-design-3477
https://gist.github.com/jboner/2841832
number of read/write , requests , transactions , n/w bw , number of requets a server has to serve number of servers needed