The objective of the Capacity Management Process  is to provide the necessary capacity for data processing and storage at the right time and in a cost-effective form, ensuring an appropriate balance of capacities in the IT organization. Good Power Management eliminates panic purchases at the last minute or the purchase of the largest system “just in case of fire”. Such situations are costly. Many data centers, for example, constantly work with underload of 30-40% or more. This is not so bad if you have a small number of servers. But if you have hundreds and thousands of servers, like many IT organizations at an enterprise, then these percentages mean the loss of huge financial resources.
Capacity Management is responsible for resolving the following issues:
• Are the costs of acquiring data processing capacity in terms of business needs justified, and are these capacities used in the most efficient way (cost-performance ratio)?
• Do the available capacities adequately match current and future customer needs (supply-demand ratio)?
• Do existing capacities operate at maximum efficiency (performance tuning)? When exactly is it necessary to install additional capacity?
To fulfill the tasks of the Capacity Management Process, close communication with business processes and IT strategy is necessary. Therefore, this process is both reactive (measuring and improving) and proactive (analyzing and predictive).
The important concepts of power management include:
• Performance Management: measuring, monitoring and tuning the performance of IT infrastructure components.
• Definition of hardware for the application (Application sizing): determine the hardware capacity or network bandwidth required to support new or modified applications with the expected workload.
• Modeling: use analytical or simulation models to determine the power required for an application and develop the best solution. Modeling allows you to analyze different scenarios and ask questions “what if?”.
• Capacity Planning: developing a Capacity Plan, analyzing the current situation (preferably using scenarios) and forecasting the future use of IT infrastructure and the resources needed to meet the expected demand for IT services.
The Capacity Management process aims to continuously provide the necessary IT resources that meet the current and future needs of the customer, at the right time (where they are needed) and at an affordable price.
Therefore, for the Capacity Management Process, it is necessary to understand both the expected development of the customer’s business and the predicted technical development. The Capacity Management process plays an important role in determining return on investment and justifying costs.
Benefits of using the process 
The benefits of implementing the Capacity Management Process are:
• reduction of risks associated with existing services, as well as effective resource management and continuous monitoring of equipment performance;
• reducing the risks associated with new services, because as a result of the configuration of hardware for the application (application sizing), the impact of new applications on existing systems is known. The same applies to modified services;
• cost reduction, since investments are made at appropriate points in time, not too early and not too late, which means that purchases do not have to be made at the last minute or buy more power for the future, before they are needed;
• reducing the risk of disrupting business processes by working closely with the Change Management Process when determining the impact of changes on IT and telecommunications facilities and preventing emergency changes due to incorrect calculation of the facilities;
• compilation of more accurate forecasts for the accumulation of information by the Capacity Management Process, which allows for quicker response to customer requests;
• the growth of rationality  of work due to the early achievement of a balance of supply and demand;
• Managing Costs or even reducing costs associated with the capacity of funds, due to their more rational use .
These benefits lead to improved customer relationships. The Capacity Management process interacts with the customer at an early stage and makes it possible to anticipate his requirements. It also improves relationships with suppliers. Procurement, supply, installation and maintenance can be planned more efficiently.
Like many ITIL library processes, Power Management originates from the era of large computers. Because of this, unfortunately, some consider that Power Management is necessary only in an environment of large computers. The underestimation of the process is aggravated by a significant decrease in the price of hardware in recent years. As a result, many simply buy hardware with excess capacity without implementing Power Management. The danger is that the greatest source of costs, risks and possible problems in IT is not the hardware itself. In other words, an unnecessary build-up of hardware creates management problems that cost more than the hardware itself.
The implementation of the Capacity Management Process will help prevent both unnecessary investment and the carrying out of capacity changes at random , since the latter aspect can particularly adversely affect the provision of services. Currently, the cost of IT consists not so much of an investment in the power of IT assets, as of managing them. For example, an excessive increase in disk storage capacity affects backup to external tape media, since searching for archived files on the network will take longer. This example illustrates an important aspect of the Capacity Management Process: quality Capacity Management is probably the most important factor for changing the perception (and reality) of an IT organization: not as a group that increases overhead, but as a service provider. With good Capacity Management, the IT service provider will see, for example, that the eighteen strategic initiatives outlined in IT this year will require a new backup solution. Understanding this, the Head of the Capacity Management Process can determine the real cost of these initiatives, that is, take into account that the cost of a new backup solution is distributed across these eighteen initiatives. This will be a proactive decision. On the other hand, in the absence of Capacity Management, the IT organization will respond only after the backup capacity has been exhausted. In this case, the customer will perceive IT costs as overhead, and the IT organization as “begging for money,” simply because it did not act proactively in setting and managing customer expectations and planning costs in advance.
The Capacity Management process aims to prevent unexpected and hasty purchases by making better use of available resources, on timely capacity expansion and on managing the use of current capacities. This process can also help in coordinating the various components of the service, which will ensure the rational use of investments in the respective components.
Modern IT infrastructure is extremely complex. This leads to increased dependencies between the powers of its components. As a result, it becomes more difficult to provide service to the customer at an agreed level. Therefore, a professional IT organization should use an integrated approach to capacity management.
The Capacity Management process consists of three subprocesses (or levels) of capacity analysis:
• Business Opportunity Management – the task of this subprocess is to understand the future needs of users. It can be achieved by obtaining information from the customer, for example from his strategic plans or by analyzing trends. This subprocess is proactive. It has a close relationship with the Service Level Management process in determining and negotiating service agreements.
• Service Capability Management – the objective of this subprocess is to determine and understand the level of use of IT services by customers (products and services provided to customers). To conclude a suitable Service Level Agreement and guarantee its implementation, it is necessary to know the performance indicators and peak load on the system.
• Resource Capacity Management – the task of this subprocess is to identify and understand the use of IT infrastructure. Examples of resources include network bandwidth, data processing power, and disk storage capacity. For effective  Resource Management, it is necessary to identify potential problems in advance. You must also be aware of the trends in the development of IT infrastructure. Within this sub-process, an important activity is the active monitoring of development trends.
Since the Capacity Management Process and business needs are interconnected, Capacity Management is an essential element of the planning process. However, the support provided to them for operational processes cannot be underestimated . Below are the links between this process and other Service Management processes.
Relationship with the Incident Management Process
Incident Management informs the Capacity Management process about incidents caused by problems with the capacity of IT tools. Capacity Management can provide Incident Management templates (methods, steps and actions)  to diagnose or solve these problems.
Relationships with the Problem Management Process
Capacity Management supports the Problem Management Process in its both reactive and proactive activities. The Capacity Management Toolkit, information gathered during its operation, knowledge and expertise can be used to support the Problem Management Process at various stages.
Relationship with the Change Management Process
Employees participating in the Capacity Management Process may be members of the Change Advisory Board . Capacity Management can provide information on capacity needs and the potential impact of changes on service delivery. The change information is the input to the Capacity Plan . During the development of this plan, the Capacity Management Process may send a Request for Change (RFC) .
Relationship with the Release Management Process
The Capacity Management process supports release scheduling when using computer networks to replicate them automatically and manually.
Relationship with the Configuration Management Process
There is a close relationship between the Capacity Database  (CDB) and the Configuration Database (CMDB). The information provided by the Configuration Management Process is essential for the development of an efficient capacity database.
Relationship with the Service Level Management Process
The Capacity Management Process provides recommendations to the Service Level Management Process on the issue of the realism of the Service Levels being discussed (for example, the application response rate). Capacity Management measures and monitors performance and provides control information to verify the performance of the agreed Service Level, and, if necessary, initiates a change in the Service Level and prepares the necessary reports.
Relationship with the IT Finance Management Process
Capacity Management supports the development of an investment plan, analysis of the ratio of income and expenses  and investment decision making. In addition, this process provides important billing information for services related to the provision of capacity, such as the allocation of network resources.
Relationship with the IT Service Continuity Management Process
Capacity Management determines the minimum capacity required to continue to provide the service in case of unforeseen circumstances. The capacity required for IT Service Continuity Management should be constantly monitored (revised) to ensure that they are consistent with daily changes in the operating environment.
Relationship with the Accessibility Management Process
Capacity Management and Access Control processes are closely related. Performance and capacity issues can disrupt IT services. In fact, the customer may consider low service performance equivalent to unavailability. Effective coordination of these two processes is necessary because of their close interdependence. They use a large number of identical tools and techniques, such as component impact analysis (Component Failure Impact Analysis – CFIA) and Fault Tree Analysis (FTA) analysis.
The following describes the activities of the Capacity Management Process, with a division for each subprocess.
Business Capacity Management includes the following types of work:
Capacity Plan Development 
The Capacity Plan describes current IT infrastructure capacities and expected changes in demand for IT services, replacement of obsolete components, and technical development plans. The capacity plan also determines the changes required to provide services at the level agreed upon in the SLA at an acceptable cost. That is, the Capacity Plan describes not only the expected changes, but also the costs associated with them. This plan should be drawn up annually and checked quarterly to confirm its relevance.
In a sense, the Capacity Plan is the most important output of the Capacity Management Process. The output often includes an annual plan, matched with a budget or investment plan, a long-term plan and quarterly plans with detailed information on planned capacity changes. Collectively, this is a set of interconnected plans where the level of detail rises as the planning time approaches.
Modeling is a powerful Capacity Management tool used to predict infrastructure trends.
The Capacity Management Process uses a wide range of tools — from assessment tools to comprehensive prototype testing tools. The first are inexpensive and often applicable in daily activities. The latter are usually suitable only for large-scale implementation projects.
Between these two poles there are a large number of approaches that are more accurate estimates and cheaper than large experimental layouts. In order of increasing their value, they include:
• trend analysis (the cheapest way);
• testing versus some base case , also called benchmarking (gives the most accurate estimate).
Trend analysis can be used to obtain permissible load information, but not to predict the response time of an application. Analytical and simulation modeling have their advantages and disadvantages. For example, simulation modeling can be used to accurately predict the performance of a central computer , possibly as part of work to determine the necessary size of the technical platform for software operation . However, this method is time consuming. Analytical mathematical modeling usually takes less time, but the information obtained at the output is less reliable. Testing in comparison with some basic variant (benchmarking) means that an environment with real conditions is being created, for example, in the vendor’s computing center. This environment satisfies performance requirements and is used to simulate what-if type or simulate change. For example, such as “what happens if an application component is transferred to another computer system?” Or “what happens if we double the number of transactions?”.
Determining the size of the technical platform for software operation 
At this stage, the hardware configuration is determined, which is necessary for the operation of new or modified applications, for example, those that are under development or that can be purchased at the customer’s request. These calculations provide information on the expected level of performance, the necessary hardware and costs. This procedure is particularly relevant in the initial stages of software development. Clear information about the required hardware and other IT resources, as well as the expected costs at the initial stage, is valuable for management. It also helps in developing prototypes of new Service Level Agreements (SLAs).
Work on determining the size of the required technical platform may require considerable effort in large companies or in organizations with complex IT infrastructure. At the beginning, as part of the Capacity Management Process, there is an agreement with the developers of the Service Level Requirements, which must be implemented using the product. When the product reaches the acceptance test stage, it checks whether the required level of service is achieved in terms of central processing unit (CPU) performance, input / output (I / O) devices, networking, disk and RAM usage.
One of the results of the stage to determine the size of the technical platform are the workload indicators. They can be used to predict the required capacity, for example, what happens if the number of users increases by 25%. Other indicators of workload are power requirements over time (peak loads during the day / week / year and prospects for future growth).
These sub-processes include the same activities, but with a focus on various aspects. Service Capability Management addresses the provision of IT services, and Resource Capacity Management addresses the technological aspects of their provision. Activities are shown in Fig.
Monitoring of infrastructure components is carried out in order to ensure compliance with agreed Service Levels. Examples of resources that may be monitored are the use of processors (CPUs), disk, network, number of licenses (i.e., for example, there are only ten free licenses), etc.
Monitoring data must be analyzed. You can use trend analysis to predict future use. The results of the analysis may lead to the start of work to improve the rationality of use or the acquisition of additional IT components. Activity analysis requires deep knowledge of the entire infrastructure and business processes of the company.
Tuning is performed to optimize systems for the current or expected workload based on the results of the analysis and interpretation of monitoring data.
The purpose of the implementation is to enter the modified or new capacity. If this is associated with a change, then the implementation involves the Change Management Process.
Demand management focuses on IT capacity consumption issues. Demand Management is engaged in studying the influence of various factors on demand. A simple example: a user runs a poorly-written SQL report in the middle of the day, blocking other users from accessing the database and generating exorbitant traffic. The Manager of the Power Management Process offers to start the task of drawing up a report at night, so that the user gets the result on his desk in the morning.
Let’s make a distinction between the Management of Short-term and Long-term Demand:
• Managing Short-Term Demand – in the event that in the near future there is a threat of a recurring lack of capacity of IT tools and if access to additional capacity is difficult;
• Managing Long-Term Demand — if the cost of upgrading cannot be justified, although at certain periods of time (for example, between 10:00 and 12:00), there may be a lack of capacity.
Demand Management provides important information for the compilation, monitoring, and possibly adjustment of both the Capacity Plan and the Service Level Agreement. Demand Management can also use differentiated pricing (i.e., different tariffs at peak and non-peak times) to influence the customer.
Completing the Capacity Database (CDB)
Creating and populating a CDB database means collecting and updating technical, business, and any other information related to Capacity Management. It may not be possible to store all capacity information in a single physical database. Network and computer system managers can use their own methods. Often the CDB database contains links to various sources of information on the capacity of IT systems.
The Capacity Management process is most effective if it is closely related to other planning processes, such as Availability Management, and application development activities. Such an interconnection promotes the use of a proactive approach in the operation of the Capacity Management Process.
The management reports submitted by the process contain, on the one hand, information on Process Management in terms of the Plan’s capacity indicators, resources used to implement the process, and process improvement activities; and on the other hand, deviation reports on issues such as:
• discrepancies between actual and planned capacity utilization;
• trends in discrepancies;
• impact on Service Levels;
• the expected increase / decrease in capacity utilization in the short and long term;
• thresholds at which achievement will require the acquisition of additional capacity.
Capacity Management depends on the following critical success factors:
• accurate assessment of business plans and customer expectations;
• Understanding IT strategy and planning, as well as planning accuracy;
• evaluation of the ongoing technical developments in the company;
• interaction with other processes.
The following parameters can serve as Key Performance Indicators (KPIs) of the Capacity Management Process:
• Predictability of customer needs: identifying changes in workload and trends, as well as the accuracy of the capacity plan.
• Technology: various options for measuring the performance of IT services, the pace of introduction of new technologies and the ability to continuously implement Service Level Agreements (SLAs) even when using old technological tools.
• Costs: reducing the number of urgent purchases, reducing unnecessary or expensive overcapacity and making investment plans at an early stage.
• IT operations : a reduction in the number of incidents due to performance problems, the ability to meet customer demand at any time and the degree of seriousness in the company’s attitude to the Capacity Management Process.
The role of the Capacity Management Process Manager is to lead the process and to ensure the development and maintenance of the Capacity Plan, as well as to ensure the up-to-date capacity database (CDB).
System, network and application managers also play an important role in the Power Management Process. Not only are they responsible for optimizing performance, they are also expected to use their professional knowledge to transform business needs into systems  system load and determine the necessary IT facilities based on them.
The potential problems of the Capacity Management Process are as follows:
• Unrealistic expectations — developers , managers and customers often have unrealistic expectations due to a lack of understanding of the technical capabilities of applications, computer systems, and networks. One of the objectives of the Capacity Management Process is to direct these expectations, for example, by educating developers about the impact of their development (for example, a database) on the capacity of IT tools and their performance. The effect of the Capacity Management Process can also be overestimated, especially with regard to system configuration and workload scheduling. If the work of the system requires a significant adjustment, then most likely the reason is the flaws in the design of the application or database. In general, tuning cannot be used to achieve a higher level of performance than the one the system was originally designed for. Most large IT systems have load scheduling algorithms that are usually more efficient than involving system managers. And of course, there are also costs associated with tuning: for a highly paid engineer, it does not make sense to spend weeks on achieving a 3% improvement in performance, if an expansion of $ 100 memory gives an improvement of 10%. Even more expensive is the cost of managing systems that are not “as simple as two and two”. Excessive “jerking” of parameters on various blocks, applications or databases can lead to unintended consequences and will increase the delay of all service management processes, as well as maintenance and troubleshooting.
• Lack of relevant information – it is often difficult to obtain the necessary information, for example, for the Capacity Plan. It may be difficult to obtain reliable information about the expected workload, as the customer’s plans are unknown or almost unknown, especially in details. It also causes difficulties for the customer, as the product’s life cycle becomes shorter. The only solution is to make the best possible estimates and periodically update them when you get more information.
• Information from the supplier – in the absence of information on the history of the issue (for example, when a new system is purchased), the Power Management becomes dependent on the information provided by the suppliers. Suppliers typically use test results  to provide information about their systems, but because of the large differences in test methods, it is often difficult to compare the information, and it can be misleading about the actual performance of the system.
• Implementation in complex IT environments – implementation in complex distributed environments is a difficult task, since a significant number of technical interfaces create a large number of interdependencies of performance parameters.
• Determining the appropriate level of monitoring – monitoring tools often have many options and can provoke overly detailed studies. When purchasing and using these tools, it is necessary to decide in advance at what level of detail the monitoring should be conducted.
These problems are relevant to the day of the Power Management of computer systems, as well as networks, large printer centers and telephone PBX systems . This can cause even more difficulties if several areas are responsible for these areas, which can lead to conflicts in responsibility for Capacity Management.
The costs of commissioning a Capacity Management should be determined in preparation for the implementation of the process. These costs can be divided into the following groups:
• procurement of hardware and software, such as monitoring tools, capacity database (CDB), modeling tools for simulation and statistical analysis, and report generation tools;
• The costs of project management for the implementation of the process;
• personnel, training and support costs;
• room, etc.
After starting the process, there are ongoing staff costs, service contracts, etc.
ITIL is a registered trademark of CCTA / OGC
The term “IT Service Management”, on the one hand, is used as a synonym for the term “IT Service Management”, but, on the other hand, strengthens it, bearing in mind the centralized approach to managing the entire IT organization as a modern service unit aimed at providing services to the business unit and being an integral part of the production process.
Empowerment – this English term has a very broad meaning and implies the “strengthening” of the team by giving it confidence, granting additional powers, organizing access to accumulated knowledge, etc.
Capacity Management – a more accurate translation is Capacity Management,