Configuration Management Database · Topic 1 of 1
The CMDB in ITSM Processes
How ServiceNow ITSM uses the CMDB for CIS-ITSM: CIs, classes, relationships, the Configuration item field, Affected CIs, Impacted Services and offerings.
- 5 min
- CIs live in class tables under cmdb_ci; relationships live in cmdb_rel_ci.
- Incident, problem and change forms have Configuration item, Service and Service offering fields.
- Affected CIs (task_ci) are added by people; Impacted Services/CIs (task_cmdb_ci_service) are calculated from relationships.
What it is
The Configuration Management Database (CMDB) stores configuration items (CIs), the hardware, software, applications and services that IT manages, and the relationships between them. Each CI belongs to a class, a table in a hierarchy that starts at the base table cmdb_ci.
ITSM does not build the CMDB, but it depends on it. Incidents, problems and changes point at CIs and services, and the platform uses those links and the relationships behind them to work out impact, risk, conflicts and who should handle the work.
How it works
CIs, classes and relationships
| Element | What it is | Example |
|---|---|---|
| CI | One record for a managed item | A specific Linux server |
| Class | The table that defines the CI's type and fields | Linux Server, which extends Server and, further up, the base CI table |
| Relationship | A typed link between two CIs, stored in cmdb_rel_ci | "Runs on", "Depends on" |
Class inheritance means a Linux server has every field of a server and of a basic CI. Relationships are what let the platform move from one broken component to the services that depend on it.
Services and offerings from CSDM
Under the Common Service Data Model, business services and technology management services describe what is delivered, and service offerings (service_offering) describe the specific level or variant, such as a regional or Gold offering. Application services represent the deployed instance of an application.
Incident, problem and change forms carry a Service field and a Service offering field next to the Configuration item field. CSDM recommends that operational tickets point to the service offering and the CI, so reports and routing follow the service structure.
Where each process uses the CMDB
| Process | CI use |
|---|---|
| Incident | Configuration item, Service and Service offering show what is broken and who is affected; CI data can drive assignment |
| Problem | The CI links related incidents, so recurring failures on one CI or service stand out |
| Change | The CI drives risk, conflict detection and approvals; Impacted Services/CIs shows what depends on it |
| Request | Catalog items can ask for the CI or service concerned through a reference variable |
The Configuration item field and the two related lists
The main Configuration item field holds one CI. Two related lists on task records widen it:
| Related list | Filled by | Table |
|---|---|---|
| Affected CIs | People, adding every CI the task touches | task_ci |
| Impacted Services/CIs | The platform, calculated from CI relationships, for example with Refresh Impacted Services | task_cmdb_ci_service |
On a change, conflict detection uses the CI and its parent or child CIs, and risk calculation uses the CI's data. Changing the CI and recalculating risk can change the approvals.
CI data that drives routing
CIs commonly hold a support group and a managed by group. A frequent ITSM requirement is to assign an incident to the support group of its CI, configured with an assignment rule or an assignment data lookup. The CI's operational status helps agents see whether a CI is in use or retired before they work on it.
What ITSM does not need from you here
Discovery, Service Graph Connectors, identification and reconciliation, and CMDB health are covered by the CIS-Data Foundations certification, which is a prerequisite for this exam. For CIS-ITSM, focus on which fields and lists the processes use and what goes wrong when CI data is poor.
How the exam asks about this
- "The change manager wants every business service that depends on the server being patched listed on the change." Use Impacted Services/CIs, calculated from CI relationships.
- "An agent fixing an incident also touched two other servers and wants them recorded." Add them to Affected CIs.
- "Incidents should go to the team that supports the CI by default." Use an assignment rule or data lookup based on the CI's support group.
What to remember for the exam
- CIs live in class tables under cmdb_ci; relationships live in cmdb_rel_ci.
- Incident, problem and change forms have Configuration item, Service and Service offering fields.
- Affected CIs (task_ci) are added by people; Impacted Services/CIs (task_cmdb_ci_service) are calculated from relationships.
- On a change, the CI drives risk, conflict detection and approvals.
- CSDM recommends tickets reference the service offering and the CI.
- Discovery and CMDB governance belong to CIS-Data Foundations, not this exam.
Most ITSM impact and risk problems are CMDB data problems. A missing relationship hides an impacted service, and the change approvals then miss the people who should have approved.
Common mistakes
Filling Impacted Services by hand only. The list is meant to be calculated from CI relationships. Manual entry misses dependencies and goes stale.
Pointing tickets at a business application. A business application is portfolio data. Operational tickets should point to the application service, the infrastructure CI and the service offering.
Assuming the CI field holds several CIs. It holds one CI. Further CIs a task touches belong in Affected CIs.
Check yourself
Which related list records the CIs that people add to a task?
Affected CIs, stored in task_ci. Impacted Services/CIs is calculated from relationships instead.
Why does changing the CI on a change request matter for approvals?
Risk depends on the CI, so recalculating risk on the new CI can change the decisions in the approval policy and the approvals required.
Which table stores the relationships between CIs?
The cmdb_rel_ci table, which holds typed links such as Runs on and Depends on.
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