There are a number of ITIL processes that go hand in hand, like incident and problem management, change and release and deployment management. But the pair that leads this list is availability and capacity management processes.
Availability management looks at services from an overall uptime perspective, while capacity management is concerned with the capacities involved. While both are vital, capacity management trumps availability in terms of depth and complex nature by a long shot. Unless there is sufficient capacity, you won't have availability.
Capacity management ensures that the current IT capacity is optimal in all areas of concern, in a cost-justifiable manner, and with an eye toward future requirements.
For example, suppose a database is filling up 2 GB of space every day, and the free space on the hard disk is 100 GB. It would take around 50 days for the limit to be breached. The capacity is sufficient as of today, and needs to be tweaked before the 50th day comes calling. The analysis surrounding capacity forecasts, and ensuring no mishaps take place because of capacity issues, is capacity management process in action.
Sub-processes of capacity management
Capacity management is a complicated process. It has three sub-processes: Component capacity management looks at it from individual component level, service capacity management from a service level and business capacity management from an overall business perspective.1. Component Capacity Management - Components are individual infrastructure elements of IT service, like hard disks, network bandwidth, processors, workstations, network connections, etc. One of the prime objectives of component capacity management is monitoring components to ensure that sufficient capacity is on hand to perform the respective functions optimally. Forecasting future component requirements plays into this as well.
By forecasting future capacities, component capacity management can prevent capacity-related incidents, thereby reducing downtime.
It may not always be about adding additional infrastructure when you need more capacity. There are tuning techniques that can leverage the existing infrastructure to meet future requirements. Let's say there are two servers in the picture. While one is mostly overloaded, the other is relatively free. You can share the load between the two servers by monitoring various technological components, optimizing the usage by tuning them appropriately, predicting future capacities and preventing capacity related incidents.2. Service capacity management - IT services include email, Internet, telephony, blackberry messaging, etc. In the previous sub-process, we looked at the capacity levels of individual components - servers, routers, switches, et al. Service capacity management involves doing a similar set of activities across a service. So, on an email service, the capacity management objective is to ensure that there is sufficient capacity for the email service to function normally. This may translate into drilling down to individual servers, gateways and load balancers, and ensuring that their capacities are fine-tuned to provide overall optimum capacity for the service.
Generally, service level agreements (SLA) deal with service capacities, and not component capacities. Once your service capacity is defined, component capacities are to be aligned to meet your service requirements.
Monitoring and recording capacities of components and services requires specialized, expensive tools. Because of this, larger enterprises have an edge over the smaller ones in implementing capacity management.
Service capacity management involves monitoring end-to-end service capacity against the agreed SLA. You report breaches if they are any and forecast possible issues by analyzing the changes going into a service.3. Business capacity management - Business capacity management isn't about monitoring the capacity of the business processes to follow suit with the other sub-processes. Instead, this process is linked to the demand that comes from the business and ensuring that the supply is in place when the business needs it.
This sub-process directly aligns IT with business, and acts as a feeder for service and component capacity management processes.
The main objective of business capacity management is to ensure that future business requirements are translated into quantifiable IT services. It's also involved in designing, planning and implementation of the service on time.
Business capacity management requires understanding service level requirements from the capacity perspective, interpreting the capacity requirements for services and component capacity management processes, assisting with agreeing SLAs, designing, amending and implementing service configuration and controlling major changes done to services.
Interface with demand management
The business capacity management process interfaces with demand management. Demand management feeds the business information necessary to carry out capacity management activities. Likewise, business capacity management provides inputs on where capacities can be optimized and influence demand - to ensure that the available capacity is not wasted.
Let's say that a cell phone service provider'snetwork is generally completely utilized between 9am and 9pm. The current utilization levels are on the higher side, which is calling for additional infrastructure to be procured and installed, along with the costs involved to expand the bandwidth. Between 9pm and 9am, utilization is well below the normal levels.
To make optimum use of the existing infrastructure, the provider needs to induce demand between 9pm and 9am, and hope that some of the load from the peak hours gets shifted to off peak hours.
The provider can influence demand by offering the use of bandwidth in off-peak hours for a fraction of the original charges, or maybe even free if this helps unload some capacity from peak hours.
Almost all cell phone service providers are following this technique to influence demand, and save themselves a significant cost of investment to upgrade infrastructure, even if it means sacrificing a small part of their revenue.
The information on the idle and peak capacities comes from the business capacity management process, and demand management works closely with it to optimize and create demand.