Numbers to Know

The figures you estimate with. Latency, storage, and what an availability target actually costs.

1. 01

   Latency Reference

   0/3

   Orders of magnitude that justify every caching and colocation decision.

   1. The Ladder from Cache to Cross-Region3 min
   2. Ratios Beat Absolute Values3 min
   3. Spending Latency Numbers in an Interview3 min
2. 02

   Storage & Throughput

   0/3

   Reference numbers for back-of-envelope storage and bandwidth calculations.

   1. Sizing Data Honestly3 min
   2. What One Machine Can Do3 min
   3. From Estimates to Architecture3 min
3. 03

   Availability Nines

   0/3

   How many nines → how much downtime you're allowed per year.

   1. What Each Nine Allows and Costs3 min
   2. Availability in Chains2 min
   3. The Math of Redundancy3 min
4. 04

   Estimation Rules of Thumb

   0/3

   Formulas to quickly size any system in an interview.

   1. The Arithmetic Toolkit3 min
   2. A Worked Estimate, Start to Finish2 min
   3. Sanity Checks That Catch Bad Numbers3 min