A CMDB full of duplicate servers, stale network devices, and incomplete application records undermines every process that depends on accurate configuration data. This guide walks you through running health checks to identify problem CIs and get actionable cleanup data.
Why CMDB data degrades over time
Most CMDBs start clean and become unreliable as discovery tools create duplicates, automated imports bring in incomplete records, and manual processes leave CIs orphaned when assets are decommissioned. The people who depend on CMDB data — change managers approving releases, incident responders identifying affected services, and asset managers tracking hardware — make decisions based on what they see. Stale data means wrong decisions, and wrong decisions mean outages that could have been prevented.
How CMDB health checks work
ServiceNow measures CMDB health across three dimensions: completeness (required fields populated), correctness (data follows expected patterns), and compliance (records meet defined policies). The health dashboard runs these checks as scheduled jobs and scores each CI class on a 0-100 scale. You define what 'healthy' means by configuring health rules — which fields are required, what data formats are valid, and which relationships must exist. The system then evaluates your actual CI data against those rules and shows you exactly where the gaps are.
Building ongoing CMDB governance
Once you identify the worst data quality issues, the next step is preventing them from recurring. Set up automated health checks to run weekly, create dashboards for CI owners to monitor their data quality scores, and establish processes for reviewing health metrics before major changes. Production CMDBs typically add custom health rules for business-specific requirements, integrate health scoring into change approval workflows, and use health trends to identify discovery sources that consistently produce bad data.
Before you start
- •itil role or admin role
- •Discovery or other CI data sources already populating the CMDB
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Step by step
Open the CMDB Health Dashboard
Navigate to Configuration > CMDB > Health. This loads the main health dashboard showing overall CMDB health scores. You'll see three main metrics: Completeness, Correctness, and Compliance, each with percentage scores. The dashboard shows data from the most recent health check job run.
Review the health metrics breakdown
Click on each metric tile (Completeness, Correctness, Compliance) to see detailed breakdowns by CI class. Completeness shows which required fields are missing data. Correctness identifies invalid data formats or values outside expected ranges. Compliance shows CIs that violate defined business rules. Focus on CI classes with scores below 70% — those need immediate attention.
Sort by 'Number of Issues' rather than percentage to find classes with the most total problems that need cleanup.
Drill into specific CI issues
Click a CI class name (like 'Server' or 'Application') to see the individual CI records with health issues. The results table shows the specific CI, what health rule failed, and the current field values. Use the filter options at the top to narrow results by specific health rules, CI states, or managed_by groups. This is where you identify the actual records that need cleanup.
Export health check results
Right-click the results table and select Export > Excel to download the health issues for offline analysis. Include columns for CI name, sys_id, health rule failed, and current values. This export becomes your cleanup worksheet for assigning remediation tasks to CI owners or discovery administrators.
Configure health check scheduling
Navigate to System Definition > Scheduled Jobs and search for 'CMDB Health'. Open the 'CMDB Health Score Calculation' job to review the schedule. The default runs weekly on Sunday nights. For active CMDBs with frequent discovery runs, change this to daily during off-peak hours. Click Update to save schedule changes.
Schedule health checks to run a few hours after your discovery jobs complete so you're always analyzing fresh data.
Set up health monitoring alerts
Navigate to Configuration > CMDB > Health Rules to review the rules being evaluated. Each rule defines what constitutes healthy data for specific CI attributes. To get notified when health scores drop significantly, create a scheduled report on the cmdb_health_score table that emails stakeholders when overall scores fall below acceptable thresholds. Configure the report to run after health check jobs complete.
Focus alerts on CI classes that support critical services — a 10% drop in server health matters more than the same drop in printers.
Best practices
Run health checks immediately after major discovery updates or bulk CI imports to catch data quality issues before they spread through dependent processes.
Create separate health monitoring dashboards for different teams — network operations cares about network device health, while application teams focus on software CI completeness.
Don't try to fix every health issue at once — prioritize CI classes that support business-critical services and have the worst completion rates.
Establish health score baselines before making major CMDB changes so you can measure whether process improvements actually work.
Configure health rules to match your organization's actual data standards — default rules often flag valid data as problematic if your naming conventions differ from ServiceNow's assumptions.
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