What is CMS in ITIL

The Configuration Management System (CMS) in ITIL is a collection of tools and data used to collect, store, manage, update, analyze, and present data about all configuration items and their relationships. A CMS can manage multiple physical configuration management databases (CMDBs). Its underlying structure is defined by the Configuration Model, a logical model of the service assets of the IT organization.

Let's first look at definitions from official sources (for example, the ITIL Glossary):
CMDB (Configuration Management Database) - A database used to store configuration records throughout their life cycle. The CMS maintains one or more CMS databases, each database stores CI attributes and relationships with other CIs.

What is CMS in ITIL

CMS in ITIL is part of the general knowledge management system for services, includes tools for collecting, storing, managing, updating, analyzing and presenting information about all configuration items and their relationships. The ITIL CMS can also include information about incidents, problems, known bugs, changes and releases. The CMS in ITIL is supported by the Service Asset and Configuration Management process and is used by all IT Service Management processes.

ITIL 4 Complete Certification Kit PDF
ITIL4 Foundation Complete Certification Kit Publisher: Axelos The ITIL 4 Foundation certification was designed as an introduction to ITIL 4

SKMS (Knowledge Management System for Services) - A set of tools and databases that are used to manage knowledge, information and data. The service knowledge management system includes a configuration management system, along with other information systems and database toolkits. A service knowledge management system includes tools for maintaining, managing, updating, and presenting all the information that an IT service provider needs to manage the entire IT service lifecycle.

What is CMS in ITIL

It follows from the definitions that:

    CMDB is part of ITIL CMS and CMS is part of SKMS. WhereinCMDB contains information about CUs and the relationships between them (and not necessarily about all CUs that are taken into account as part of the Configuration and Service Assets management process)The CMS contains CMDB, records of incidents, problems, known bugs, changes and releases (and here there is already information about all CUs that are taken into account as part of the Configuration and Service Assets management process)SKMS contains the CMS in ITIL, as well as all the tools and databases that we use to manage the provision of the service in the required form and on the required conditions.

And now about life. Personally, I see implementations like this in the real world:

CMS is, for example:

Option 1. ITSM-System, which includes CMDB, and also allows you to work with records of incidents / problems / changes, etc. For example, this one or this one, but not this one (because there is no CMDB in it);

Option 2. A set of different CMDBs and ITSM-system (or even just a bug-tracking program);
Option 3. Just one CMDB, provided that it contains all the CUs taken into account in the process of managing configurations and service assets, and all the information necessary for them;

CMDB is, for example:

Option 1. Exel-file with a list of all servers, information systems and licenses, as well as with records of which IP is on which server and which license belongs to which IP;
Option 2. A more complex program for accounting KE and their connections like this one;

SKMS is, for example:

Option 1. Just an ITSM system, if this is enough to manage support, development and delivery of our services;
Option 2. ITSM system, knowledge base, several monitoring systems, some kind of portal for service users, billing system, labor accounting system and anything else that is needed to manage support, development and provision of our services;

ITIL CMS / CMDB - Configuration Management System, Configuration Management Database Model The CMS is used to store information about all configuration items (CIs) under the control of configuration management.
CIs can be of different types: CMS almost always covers IT services and infrastructure, but can also cover other types of items such as policies, project documentation, employees, vendors, etc

The configuration management system (CMS) is a set of tools and databases for managing the configuration data of an IT service provider. The CMS also contains information about incidents, problems, known bugs, changes and releases; and can contain data on employees, suppliers, locations, business units, customers and users. The CMS includes tools to collect, store, manage, update and present data on all CIs and their relationships. The CMS is managed by the configuration management process and used by all IT service management (ITSM) processes.

Configuration Management Database (CMDB), CMS, and ITSM are definitions introduced by the IT Information Library (ITIL), a set of best practices for IT. ITIL was first developed in 1989 by the British Office of Government Commerce (OGC) and is currently in version 3. ITIL can broadly be viewed as a set of guidelines for the management and operation of IT. The ITIL v3 model emphasizes services and processes as well as the interactions and transitions between them. Service operations are the set of interacting processes that culminate in the provision and availability of a service. Services can include a number of core processes and other services. ITSM is the set of processes that manage service operations. For example the maintenance, updating and repair of service components.

CMS functions

A CMS offers the following functions:

Item Configuration - This function enables the identification and control of configuration items (CI).
Service configuration: With this function, collections of configuration items can serve as a model of a service that can be controlled and configured as a whole.
Federation and Integration: This function provides integration, mapping, modeling and data discovery functions and provides APIs for providing and using configuration data between providers and consumers.

In terms of ITIL v3, the CMDB in one of the many Managed Data Repositories (MDRs) is out of date - the "CM" part is deleted so that more or less the "DB" part remains. However, the v3 definition omits a critical functionality level from the CMDB definition that is not yet defined in the "CM" part. Example: Service Asset and Configuration Management (SACM). A CMDB is more than an MDR. Valid CMS solutions still have CMDB-like components to provide this expected additional functionality, which includes:

A data integration hub that provides channels for consumers and suppliers to exchange configuration data. These ladders are implemented as federation adapters, APIs, web services, or other I / O methods.
Analytical functions such as impact analysis, comparison of gold masters, audit and compliance and other forms of reporting.

A CI model that can represent business and IT services and components (such as infrastructure, applications, networks, databases, business processes, and business services) and the relationships and dependencies between these services and components.

Service modeling and topology visualization.Detection and dependency mapping.CMS value chain

Configuration management requires an investment to enable the value chain. Configuration management can be a manual process that uses no technology, or it can rely on non-specific tools like Excel spreadsheets. Customers need to understand the value chain in order to optimize their configuration management investments.

This investment can be justified as enabling technology that supports another use case such as Closed Loop Incident Process (CLIP) or Change, Configuration and Release Management (CCRM). Alternatively, vision-based companies can invest directly in configuration management as a strategic basis to meet the general use cases of ITSM and SACM.