You are currently viewing CMDB Parent-Child Relationship – Myth Buster

CMDB Parent-Child Relationship – Myth Buster

In CMDB, we take relationships lightly, even though they are one of the most powerful features. Without relationships, a CMDB is just a spreadsheet. When looking at any relationship, we often call it a parent-child relationship. This is quite convenient because we are talking about two CIs with some dependency and call one parent and the other a child depending on their authority.

However, it is not always a parent-child relationship; there are other categories of relationships between Cis. In this article, I will focus on categorising relationships based on their dependencies. It is important to understand the relationship category because, after that, only we will be able to estimate the accrual impact analysis.

Parent-child relationship

In a Configuration Management Database (CMDB), a parent-child relationship represents a structural or hierarchical connection between different Configuration Items (CIs). In this context, a parent CI is a higher-level entity that contains or governs one or more child CIs, which are lower-level entities that are dependent on or associated with the parent CI. The parent-child relationship reflects the way these CIs are organised and the dependencies between them within an organization’s IT environment.

In simpler terms, the parent-child relationship in a CMDB mirrors how certain components or assets are grouped, with the parent CI serving as a container or controller for the child CIs. This relationship helps in modelling and managing complex IT infrastructures and understanding how changes or issues in one component can affect others.

For example, consider a CMDB for an organization’s data centre:

Parent CI: Data Centre Rack A

  • Description: This represents a physical rack within the data centre.

Child CI 1: Server 1

  • Description: A physical server hosted within Rack A
  • Dependency: It relies on the power and network connections provided by Rack A.

Child CI 2: Server 2

  • Description: Another physical server hosted within Rack A.
  • Dependency: It also relies on the resources provided by Rack A.
Parent CI: Data Center Rack A
   |
   ├─ Child CI 1: Server 1
   |   └─ Dependency: Power, Network
   |
   ├─ Child CI 2: Server 2
       └─ Dependency: Power, Network

In this scenario, “Data Centre Rack A” is the parent CI, and “Server 1” and “Server 2” are child CIs. The parent-child relationship signifies that the servers are physically located within Rack A and depend on it for power and network connectivity. This representation helps IT teams manage and understand the relationships between components in the data centre efficiently.

Dependency Relationship

- Web Application
  - Depends on: Database Server

Explanation:

  • The “Web Application” CI depends on the “Database Server” CI, indicating that the web application relies on the database server to function.

Associative Relationship

- CRM Software
- Accounting Software
- Associated with: Database Server (Common DB)

Explanation:

  • Two software applications, “CRM Software” and “Accounting Software,” are associated with a common database server labelled as “Database Server (Common DB).”

Composition Relationship

- E-commerce Application
  - Front-end Component
    - Web Server
  - Back-end Component
    - Application Server
  - Database Component

Explanation:

  • The “E-commerce Application” CI is composed of three components: front-end, back-end, and database.
  • Each component further breaks down into specific CIs like web servers and application servers.

Connectivity Relationship

- Network Switch
  - Connected to: Server 1, Server 2, Router

Explanation:

  • The “Network Switch” CI is connected to “Server 1,” “Server 2,” and a “Router,” indicating the physical connections between these CIs.

Containment Relationship

- Data Center Server (Server A)
  - Contains: VM 1, VM 2
    - Contains: Web Application, Database

Explanation:

  • “Data Center Server (Server A)” contains two virtual machines (VM 1 and VM 2), and each virtual machine contains specific applications and databases.

Service Relationship

- Email Service
  - Includes: Email Servers, Database Server, User Authentication

Explanation:

  • The “Email Service” CI includes various components like email servers, a database server, and a user authentication system as part of the service.

Configuration Item (CI) Relationship

- Web Server Cluster
  - Consists of: Web Server 1, Web Server 2, Web Server 3

Explanation:

  • The “Web Server Cluster” CI consists of three individual web servers (Web Server 1, Web Server 2, and Web Server 3).

These textual representations and explanations should help you understand different types of relationships within a CMDB and how they are organized hierarchically or associated with one another.

Leave a Reply