Load Balancing & Hashing by Hand: Round Robin, Weighted & Least-Connections Rules, Hash Mod N, Consistent Hashing Rings & Capacity Headroom
Understand how requests are spread across servers. You will distribute requests round robin and by weights, simulate least-connections choices, map keys to servers with hash mod N, measure how many keys move when a server is added, place servers and keys on a consistent-hashing ring, balance it with virtual nodes and size the pool with headroom, with every cell checked as you go.
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About this course
This course shows how a load balancer decides where requests go, with every rule worked out in a spreadsheet. You assign requests round robin with MOD and see the effect of uneven server speeds, build a weighted cycle from cumulative weights with XLOOKUP and step through least-connections choices with INDEX, MATCH and MIN. You map keys to servers with hash mod N, measure how many keys move when a server is added, place servers and keys on a consistent-hashing ring with MINIFS and a wrap-around, balance it with virtual nodes and STDEV.S and size a pool for a target utilisation with N + 1 headroom.
Lessons
- Round Robin: Request Number to Server with MOD, Requests per Server and Uneven Speeds Pro
- Weighted Round Robin: Weights, Expected Shares, a Weighted Cycle and Its Error Pro
- Least Connections: Open Connections per Step, Chosen Server with MIN + MATCH, Finishing Requests Pro
- Hash Mod N: Given Hash Values, Server = MOD(hash, N), Keys per Server and Imbalance Pro
- The Cost of Rehashing: From N to N + 1 Servers, Keys That Move and Why It Is So High Pro
- Consistent Hashing: Servers and Keys on a Ring, Next Server Clockwise and Keys Moved When a Server Joins Pro
- Virtual Nodes: Several Positions per Server, Arcs of the Ring, Load Spread and How Many to Use Pro
- Capacity & Failover: Servers for a Target Utilisation, N + 1, Load After a Failure and a Chart Pro