🗃️ Configuration Management Database (CMDB) & Discovery in ServiceNow

CASE STUDY 1:🌐 What is CMDB?

The Configuration Management Database (CMDB) is a centralized repository that stores information about all the configuration items (CIs) in an IT environment and their relationships. CIs can include:

• Hardware (servers, routers, laptops)

• Software (applications, OS, databases)

• Services (email, HR system, cloud services)

• Documentation and more

Purpose of CMDB:

• Maintain an accurate, real-time inventory of IT assets and services

• Understand dependencies between components

• Support IT Service Management (ITSM) processes like Incident, Problem, and Change Management

💡 Key Benefit:
With a reliable CMDB, organizations can reduce downtime, improve change impact analysis, and enhance service delivery.

⚙️ CMDB Key Concepts

• Configuration Item (CI): Any component or asset tracked in the CMDB.

• CI Class: Defines the type of CI (e.g., Server, Application, Database).

• Relationships: Links between CIs showing dependencies (e.g., a server hosts an application).

• CI Lifecycle: Tracks status from procurement, deployment, to retirement.

• CMDB Health: Measures accuracy and completeness via data quality, compliance, and normalization.

CASE STUDY 2:

📥 What is Discovery?

Discovery is a ServiceNow application that automatically scans the IT infrastructure to identify and populate the CMDB with CIs and their relationships.

How Discovery works:

• Probes scan the network to detect devices and software.

• Sensors process probe data to create/update CIs in the CMDB.

• Patterns define how Discovery finds and maps complex CIs.

Discovery reduces manual data entry and helps maintain a current, accurate CMDB.

⚡ Types of Discovery in ServiceNow

1. Basic Discovery:

   • Scans IP ranges to identify network devices, servers, and software.

   • Uses protocols like SNMP, WMI, SSH.

2. MID Server-Based Discovery:

   • Uses a MID Server installed on-premises to securely scan internal networks.

   • Essential for scanning behind firewalls or in private clouds.

3. Cloud Discovery:

   • Discovers resources in cloud platforms like AWS, Azure, and Google Cloud.

   • Uses APIs to fetch cloud resource info and populate CMDB.

4. Service Mapping:

   • Advanced form of discovery mapping business services by tracking dependencies across infrastructure layers.

   • Provides visual service maps for better impact analysis.

CASE STUDY 3: 🛠️ Advanced CMDB and Discovery Concepts

• Discovery Patterns: Customizable logic for identifying complex CIs like clustered databases, load balancers, or middleware.

• Normalization and Reconciliation: Rules to avoid duplicate CIs and merge data from multiple sources.

• CMDB Integrations: Integrate with external systems (e.g., asset management tools, cloud management platforms) to import/export data.

• Event-Driven Discovery: Trigger discovery based on system events for near real-time updates.

• CMDB Health Dashboards: Monitor CI data quality, completeness, and compliance.

📊  Use Cases of CMDB & Discovery

• Impact Analysis: Quickly understand what services or users are affected by a failed CI.

• Change Management: Assess risks before implementing changes by viewing CI relationships.

• Incident and Problem Management: Speed up root cause analysis using CI dependency maps.

• Asset Management: Track lifecycle and ownership of hardware/software assets.

• Security and Compliance: Identify unauthorized or outdated assets and maintain audit trails.

⚙️ CMDB Architecture

• Tables & Classes

  • CMDB is built on the Common Service Data Model (CSDM) and class hierarchy.

  • The cmdb_ci base table holds all CIs, extended into subclasses like:

    • cmdb_ci_computer (Servers)

    • cmdb_ci_app_server (App Servers)

    • cmdb_ci_db_instance (Databases)

• Relationships

  • CMDB doesn’t just store CIs—it stores relationships:

    • Runs on, Depends on, Hosted on, Connects to

  • This allows impact analysis when troubleshooting incidents or planning changes.

CASE STUDY 4:

🔍 CMDB Data Model & CSDM (Common Service Data Model)

• CSDM is ServiceNow’s framework for CMDB standardization.

• Provides best practice data models for structuring:

  • Services (Business Service → Technical Service)

  • Applications

  • Infrastructure

• Ensures consistency across ITSM, ITOM, ITBM, HRSD, and SecOps.

💡 Example:

• A Business Service like “Payroll” → depends on an Application Service “HR System” → hosted on VMs in AWS.

🛠️  CMDB Population Methods

1. Discovery (automated scanning of infrastructure)

2. Service Mapping (maps business services end-to-end)

3. IntegrationHub ETL (extract-transform-load external data)

4. Import Sets & Transform Maps (CSV, Excel, etc.)

5. APIs (custom integrations from asset tools, cloud providers)

📊 CMDB Health

Maintaining CMDB data quality is critical. ServiceNow provides CMDB Health Dashboards that track:

• Completeness → Are all required attributes populated?

• Compliance → Are CI values following naming/data rules?

• Correctness → Are duplicate or invalid CIs present?

💡 Example: Duplicate servers discovered by multiple data sources → Reconciliation rules determine the “golden record.”

⚡ Advanced CMDB Features

• Reconciliation Engine

  • Manages data from multiple sources, avoids duplicates, and enforces data precedence rules.

• Identification & Reconciliation (IRE)

  • Framework that ensures unique CI identification and merges incoming data correctly.

• Data Certification

  • Periodic reviews by CI owners to confirm accuracy.

• Normalization Engine

  • Cleans and standardizes vendor and model names (e.g., MSFT → Microsoft).

• Service Graph Connectors

  • Prebuilt integrations for vendors like AWS, Azure, VMware.

🔐  CMDB Governance

CMDB is only successful with governance and ownership:

• Assign CI Class Owners

• Define data entry rules

• Maintain a CMDB Policy (what to store, what not to store)

• Establish a Change Management link → update CIs only through authorized changes

CASE STUDY 5:

🛠️ Real-World Challenges

• Data Overload: Discovery might pull too much irrelevant data → requires filtering.

• Stale Data: CI updates not synced with asset lifecycle → outdated records.

• Ownership: No clear accountability for keeping CI data correct.

• Duplication: Multiple tools feeding CI data without reconciliation.

• Complex Relationships: Hard to maintain accurate dependency maps across hybrid cloud + on-prem.

💡  Best Practices for CMDB and Discovery

• Keep CMDB data accurate and up-to-date with regular Discovery runs.

• Use MID Servers for secure, scalable scanning.

• Implement service mapping for critical business services.

• Define clear ownership and governance for CMDB data.

• Regularly monitor CMDB health and resolve discrepancies.

• Use CMDB reconciliation rules to prevent duplicate CIs.

🎬 Conclusion

ServiceNow’s CMDB and Discovery together form the backbone of effective IT Service Management by providing:

• An accurate, dynamic inventory of all IT components

• Automated, secure discovery and mapping of infrastructure

• Enhanced visibility for impact analysis, change control, and incident resolution