Capacity Plan

The Capacity Plan contains different scenarios for predicted business demand and offers costed options for delivering the service-level targets as specified. This plan allows service designers to make the best choices about how to provide quality service at an affordable price point.

The Capacity Plan helps gauge the most cost effective way of provisioning resources and services by aligning them to your organization’s demands.

• Ensure that system components perform as efficiently as possible
• Describe system capacity requirements for systems and applications
• Ensure that infrastructure components can perform required functions
• Identify and reduce inefficiencies associated with under-utilized resources
• Provide a technical reference for team members
• Provide satisfactory service levels in a cost-efficient manner

The Capacity Plan is the cornerstone of the Capacity Management process, and good capacity management is an important part of the infrastructure and deployment planning. Within Service Design, many other processes are highly dependent on it: Design Coordination, Availability Management, IT Service Continuity, Information and Security Management, and others.

Many processes outside Service Design depend on it as well: IT Financial Management (Service Strategy), IT Operations Control, Application Management, and Technical Management (Service Operations).

Elements of Capacity Plan

• Scope: Having business demands (drivers) collected in a single place on one hand, and available IT resources on the other, allows organizations to identify any inefficient or wasteful resources at a single glance. Therefore, one of the first steps in writing down a Capacity Plan would be to list all business demands (drivers), and IT services supporting them. Any business services that aren’t supported by the IT organization should not fall within the scope of the Capacity Plan.
• Manage the resources required for IT service delivery: Once there is a high-level IT and business services overview, it is imperative to drill down to the actual physical resources that drive IT services. This part is fairly technical, as it includes actual hardware components (and other resources) and their inner workings, and only subject matter experts generally know its impact on a service. Physical resources will include the server’s physical properties (e.g., CPU, RAM, HDD, INAC, etc.), licensing, running modes (e.g., physical, virtual, clustering, etc.) or service level (e.g., failover, load balancing, high availability, security, etc.). These properties should be correlated as closely as possible with expected service level in terms of capacity and/or performance.

source: Advisera

• Gather and evaluate performance data: Once you have all the relevant data regarding business needs, supporting IT services, and their combined impact on service performance, you should gather the data that will compare our resources and required capacity, and record that data within the Capacity Plan. Evaluating performance data is not an easy task, and is generally performed by subject matter experts. Aside from collecting hard data, any incidents related to insufficient capacity should be recorded and evaluated alongside the performance data itself.
• Analyze the data, spot the trends, make the forecasts: Once you have all the relevant data gathered and evaluated, as time passes, it should be easy enough to spot trends that happen naturally, and determine whether they are aligned with business expectations. Those trends are the basis for making short-, medium-, and long-term expectations regarding capacity. The purpose of such monitoring is to avoid the negative business impact that a lack of capacity may present. A common example is a lack of storage space; from the moment when Incident Management records a “low disk space” alert, until you order, set up, and implement additional storage capacity (not to mention find the budget for such a scenario), you may be forced to either implement unhealthy workarounds (external USB drives) or shut down the service completely. Forecasts and what-if analyses are here to help predict and prevent such events, and respond to them in a timely manner without impact to agreed service levels.
• Improvements and recommendations: As the last chapter of the Capacity Plan, you should write down any improvements and recommendations that are the product of data gathered, trend analysis, forecasts, business plans, etc. If some service is using a less-than-expected amount of resources and trends are negative, it is up to Capacity Management to recommend its reevaluation / redesign in order to eliminate extra resources that are not used, and shave off costs. On the other hand, if new technology shows up, or trends show faster-than-expected growth in demand, Capacity Management should be the first to react and recommend an increase of required resources. The list of improvements and recommendations should be accompanied by related costs, impact analysis, expected timescale, and affected resources and drivers.