# Scaling a distributed cache: Why consistent hashing is mandatory

DevFeed: [Scaling a distributed cache: Why consistent hashing is mandatory](<https://devfeed.tech/articles/scaling-a-distributed-cache-why-consistent-hashing-is-mandatory-39578.md>)

Original publisher: [Read original article](<https://ankit-rana.com/logs/26-scaling-distributed-cache-consistent-hashing/>)

Author: hello@ankit-rana.com

Published: 2026-05-17T00:00:00Z

Content type: tutorial

Language: en

Sources: [Ankit Rana | Mechanical Sympathy](<https://devfeed.tech/sources/ankit-rana-mechanical-sympathy.md>)

Topics: [consistent hashing](<https://devfeed.tech/topics/consistent-hashing.md>), [distributed-systems](<https://devfeed.tech/topics/distributed-systems.md>), [Caching](<https://devfeed.tech/topics/caching.md>), [sharding](<https://devfeed.tech/topics/sharding.md>), [scaling](<https://devfeed.tech/topics/scaling.md>), [Database](<https://devfeed.tech/topics/database.md>), [Memcached](<https://devfeed.tech/topics/memcached.md>), [Redis](<https://devfeed.tech/topics/redis.md>)

Tags: [caching](<https://devfeed.tech/tags/caching.md>), [consistent-hashing](<https://devfeed.tech/tags/consistent-hashing.md>), [database](<https://devfeed.tech/tags/database.md>), [distributed](<https://devfeed.tech/tags/distributed.md>), [distributed-cache](<https://devfeed.tech/tags/distributed-cache.md>), [distributed-systems](<https://devfeed.tech/tags/distributed-systems.md>), [memcached](<https://devfeed.tech/tags/memcached.md>), [redis](<https://devfeed.tech/tags/redis.md>), [scaling](<https://devfeed.tech/tags/scaling.md>), [sharding](<https://devfeed.tech/tags/sharding.md>)

## AI overview

The article explains why modulo-based cache sharding can remap nearly every key when a node fails, causing a large cache miss surge and database overload. It presents consistent hashing on a fixed ring as a way to limit movement to keys assigned to the failed node, and notes that virtual nodes improve distribution across physical cache nodes.

## Source excerpt

Sharding a cache with hash(key) modulo N means the denominator changes when a node dies, remapping nearly every key. Dropping from five nodes to four invalidates about 80 percent of the cache instantly and routes that miss storm straight at the primary database. Consistent hashing maps nodes and keys onto a fixed ring so only the dead node's keys move, and virtual nodes fix the uneven distribution a handful of physical nodes would otherwise produce.