Scale OpenSearch shards online without spiking search latency

A runbook for fixing hot shards with controlled migration, aliases, parity checks, and a clean rollback path.

Learn how to diagnose hot shards, decide whether primary shard scaling is justified, and run an online OpenSearch migration without losing writes or breaking searches.

Created: August 19, 2026

Published: August 19, 2026

Estimated time45 min

LevelAdvanced

Before you startRead access to OpenSearch Dev Tools or curl against the cluster API

PlatformsLinux / Docker

WhatsApp X LinkedIn

Docker

Rehearse the flow in a local or staging cluster before touching production.

docker composeOpenSearch stagingsynthetic dataset or anonymized snapshot

Latency canary

for i in {1..30}; do curl -s "$OS/logs-write/_search" -H "content-type: application/json" -d @canary-query.json >/dev/null; sleep 2; done

Document-count parity

curl -s "$OS/logs-prod-2026.08,logs-prod-2026.08-v2/_count" | jq .

Also available inEscalar shards online en OpenSearch sin disparar la latencia de búsqueda

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