Optimize Azure Log Costs: Split Tables & Use Auxiliary Tier with DCR

Microsoft’s latest guide details how to reduce Azure Log Analytics ingestion costs by leveraging Data Collection Rule (DCR) transformations to split high-volume logs into multiple tables and route verbose, low-priority logs to the cost-effective Auxiliary tier.

Key Highlights:

Identify candidate logs

  • Review existing tables (e.g., Syslog) to find logs that can be stored in Auxiliary tier without impacting operations.

Create DCR-based custom tables

  • Use a PowerShell script to duplicate the schema of the original table.

Implement transformation logic

  • Configure DCR to route only specific log types (e.g., “Informational” Syslog entries) to the Auxiliary table while keeping critical logs in the main table.

Set retention policies

  • Define retention for Auxiliary tables during creation for cost and compliance balance.

This method can yield significant savings while maintaining necessary logs for auditing and compliance.