Introduction
Within the ever-changing world of IT infrastructure, it is essential to keep a Configuration Management Database (CMDB) up to date and accurate. The CMDB in ServiceNow is the single source of truth for IT assets, and at the heart of this is the idea of Configuration Item (CI) classification. This is essential to ensure that Configuration Items are properly classified, allowing for proper management, reporting, and dependency mapping. However, as IT environments continue to evolve, Configuration Items may change, requiring a new classification. In this blog post, the complexities of CI classification and reclassification in ServiceNow will be explored, including best practices and the use of automation to ensure the integrity of the CMDB.
1. CI Classification: The Key to a Healthy CMDB
CI Classification is the act of placing a Configuration Item into its proper category in the ServiceNow CMDB structure. For example, a generic server may first be classified as Server, but as more information is gathered, it may be further classified as Windows Server or Linux Server. This level of classification is important for several reasons:
•Data Quality: Helps ensure that Configuration Items have the proper attributes and relationships that are specific to their type.
•Better Reporting: Allows for proper reporting and analysis based on a specific type of Configuration Item, providing valuable information.
•Better Discovery: Helps discovery tools gather information and properly identify Configuration Item types.
•Proper Dependency Mapping: Helps to properly map services to their underlying infrastructure components.
Misclassification, on the other hand, can cause serious problems with data quality, making the CMDB less trustworthy and affecting IT processes.
2. What is CI Reclassification? Adjusting to Change
CI Reclassification is the occurrence of a CI's class change after its initial discovery or reconciliation. This is usually triggered by automated discovery tools or manual changes, which are a result of changes in the CI's nature or function. ServiceNow breaks down reclassification into three main types:
2.1. Upgrade: Moving Towards Specificity
In an Upgrade reclassification, a CI is migrated from a generic class to a more specific class. A typical example of this is when a Server CI is reclassified as a Windows Server or Linux Server after its operating system has been determined. This type of reclassification is usually an improvement in data accuracy because the CI can now inherit properties and relationships associated with its new, more specific class.
2.2. Downgrade: The Risk of Data Loss
On the other hand, a Downgrade is the process of transferring a CI from a particular class to a more general class (for example, Windows Server to Server). This might happen if certain characteristics are no longer applicable or if the CI's purpose is less well-defined. Downgrades also pose a risk of data loss, where characteristics specific to the more general class might be deleted or made unavailable within the generic parent class.
2.3. Switch: Navigating Peer Classes
A Switch is a type of reclassification that involves transferring a CI from one peer class to another, for example, from Windows Server to Linux Server. This is effectively a downgrade to the generic parent class (for example, Server) followed by an upgrade to the new peer class. Switches also pose a risk of attribute loss if the attributes are not shared by both peer classes.
The following is a diagram showing the different types of reclassification:
3. Automation and Discovery: The Role of IRE
The main force behind reclassification in ServiceNow is automation, especially through the Identification and Reconciliation Engine (IRE). The IRE is an important part of the CMDB and is responsible for maintaining data integrity by automatically identifying CIs and their properties from different data sources, such as discovery tools.
The IRE's reclassification process is governed by the following system properties:
•glide.class.upgrade.enabled: This is a boolean property that enables the IRE to perform upgrade reclassifications when set to true.
•glide.class.downgrade.enabled: This is a boolean property that enables the IRE to perform downgrade reclassifications when set to true.
•glide.class.switch.enabled: This is a boolean property that enables the IRE to perform switch reclassifications when set to true.
These properties enable administrators to fine-tune the reclassification process in their CMDB. Furthermore, Reclassification Restriction Rules can be set up to restrict certain class changes, offering an additional layer of control and ensuring that data is not accidentally altered.
The following diagram illustrates the overall process of the IRE related to reclassification:
Conclusion
The proper classification of CI and strategic reclassification are essential elements of a sound ServiceNow CMDB. By understanding the various methods of reclassification, such as upgrade, downgrade, and switch, and by utilizing the automation features of the Identification and Reconciliation Engine, an organization can ensure that their CMDB is highly accurate and reliable. This, in turn, enables better decision-making, improves IT operations, and ultimately leads to a healthy and efficient IT environment.
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