Seven Loki Configuration Fixes That Cut Runaway Log Storage Costs

A software team spent two development sprints optimizing their Grafana Loki log storage setup after costs grew uncontrollably due to misconfigured labels and retention policies. The biggest culprit was high-cardinality labels like trace_id and request_id, which multiplied index size rather than simply adding data volume. Splitting per-tenant retention overrides instead of using a single global policy cut storage for one noisy tenant by 70% while extending retention for compliance-sensitive logs. The team also found that tuning retention_period without enabling the compactor was effectively a silent no-op, and that increasing chunk target size to around 2MB reduced object storage PUT requests by roughly a third. Migrating high-cardinality fields to Loki's structured metadata feature, available since version 2.9, delivered the single largest reduction in index cardinality.