32 Configuration Management

I. Configuration Management

• Definition (from Wikipedia): "Configuration management is a process that tracks all of the individual configuration items in an IT system, which may be as simple as a single server or as complex as an entire IT department."
• What is a Configuration Item (CI)?
  • Any component that needs to be managed to deliver an IT service.
  • Examples: Servers, network switches, routers, software, desktops, laptops, virtual machines.
  • Can be tangible (physical hardware) or intangible (software, services).
  • Large organizations can have millions of CIs in their CMDB.
• CI Class: A category of CIs (e.g., "Servers"). Classes can have child classes (e.g., "Windows Servers," "Linux Servers"). This creates a hierarchy.
• Tables:
  • CIs are stored as records in the cmdb_ci table or one of its many extended tables.
  • Each CI class has its own table (this is crucial for relationships). There are hundreds of out-of-box CMDB tables.
• Relationships:
  • CIs can have few or many relationships to other CIs.
  • Relationships are defined using verbs that describe the connection (e.g., "supports," "depends on," "used by").
  • Upstream: Towards applications/services (e.g., "Server supports Email Service").
  • Downstream: Towards hardware (e.g., "Email Service is supported by Server").
• Purpose of a CMDB:
  • Dependency Views/Maps: Visual representations of CI relationships, showing how everything is connected. This is a key feature.
  • Troubleshooting: Helps identify the root cause of incidents and problems by showing dependencies.
  • Change Management: Reduces conflicts by showing the impact of changes on related CIs.
• CMDB Granularity: A CMDB can be as detailed as an organization needs, starting with critical components and expanding over time.
• Populating the CMDB:
  • No easy task.
  • Options:
    • Manual import (spreadsheets).
    • Automated tools (ServiceNow Discovery, Microsoft SCCM).
  • Crucial: A process for creating and updating CIs is essential to keep the CMDB accurate and valuable. A stale CMDB is not useful.

II. Demo: Configuration Management in ServiceNow

• Configuration Application: Has the most modules of any application due to the large number of CI classes.
• Application Servers (Example):
  • All module: Shows all CIs with a class of Application Server (or its child classes).
  • CI Form View: Shows the properties of a specific CI (e.g., Name, Category, Version, Managed By, Support Group, TCP Ports).
  • Related Items: Shows relationships to other CIs (this is a critical section).
• Servers (Example):
  • All module: Shows all CIs with a class of Server.
  • CI Form View: More detailed hardware-specific properties (Asset Tag, Manufacturer, OS, RAM, CPU, etc.).
  • Related Items: Shows relationships (e.g., a physical server supporting application servers).
• CI Class Manager:
  • A single interface to view the CMDB hierarchy and configure CI classes (fields, relationships, etc.). Provides a high-level overview.
• CMDB Groups: Allows creating groups for managing CIs (e.g., a "Servers Admin" group).
• CMDB Query Builder: A graphical tool for building CMDB queries.
• Business Services:
  • Services that the business relies on (e.g., Email, Trading Software).
  • Not the physical components, but the service itself.
  • Dependency View (Crucial): Shows the relationships between the business service and other CIs (upstream and downstream). This is a powerful visualization. The demo shows the Email service and its connections to servers, storage, etc.
• Mass Storage Device (Example):
  • A CI representing a storage area network (SAN).
  • Dependency View: Shows how the storage device supports many other CIs (email servers, database servers, web servers). This demonstrates the bottom-up view of dependencies.
• CMDB Dashboards: Provide charts and graphs for visualizing CMDB data (requires sufficient data to be meaningful).
• CMDB Classification Sections: The bulk of the Configuration application, listing modules for various CI classes (Application Servers, Servers, Clusters, Databases, etc.).
• Relationships Section (Important):
  • CI Relationship Types: Defines the verbs used for relationships (e.g., "depends on," "used by," "contains," "runs on"). These are pre-defined, but can be customized.
  • CI User Relationship Types: Relationships between CIs and users.
  • Suggested Relationships: Pre-defined relationships that can be applied.
• CI Identifiers: A list of identifiers for different CI types (each with its own table).
• Adding CI Relationships (Manually):
  • On a CI record, click the + button in the Related Items section.
  • This opens the Relationship Editor.
  • Shows existing relationships (Parent/Child).
  • Suggested Relationship Types: Provides a filter to find related CIs.
  • The relationship is described in both directions (e.g., "A depends on B" and "B is used by A").
  • Saving the relationship updates the Related Items and the Dependency View.
• Automated Relationships
  • Manually adding relationships is impractical for large CMDBs.
  • ServiceNow Discovery can automatically create relationships (more advanced topic).

Key Takeaways:

• The CMDB is a central repository of information about IT components and their relationships.
• CI Classes and their hierarchy are fundamental to organizing the CMDB.
• Relationships are key to understanding how CIs are connected and the impact of changes or outages.
• Dependency Views are a powerful visualization tool for understanding complex relationships.
• ServiceNow provides tools for both manual and automated CMDB management.
• Maintaining an accurate and up-to-date CMDB is essential for effective IT operations. The CMDB is a foundational element for Incident, Problem, and Change Management, as well as other ITIL processes.