availability160management(编辑修改稿)

availability160management(编辑修改稿)内容摘要：

IT services that are defined as critical business functions, even when no SLA exists.  Applying availability management to the suppliers (internal and external) that form the IT support anization as a precursor to the creation of a formal SLA.  Using availability management in the consideration of all aspects of the IT infrastructure and supporting anization that may affect availability, including training, skills, policy, process effectiveness, procedures, and tools. Note Availability management is not responsible for business continuity management and the resumption of business processing after a major disaster. This is the responsibility of the IT Service Continuity Management SMF. However, availability management is closely related and provides key inputs to IT service continuity management. Key Definitions The following are key definitions within the availability management processes: Availability. Ability of a ponent or service to perform its required function at a stated instant or over a stated period of time. Countermeasures. Actions taken to prevent or reduce the effect of an identified risk. Critical business functions. The critical elements of the business process supported by an IT service. Downtime. The unavailability of the IT service during hours that the business deems the systems to be available—as advertised within SLAs. Endtoend service. All ponents of the IT infrastructure required for delivering an IT service. High availability. Minimizing or masking ponent failures. Incident life cycle. An availability technique that analyzes the brokendown stages of an incident to allow for timing and measurement of each stage. Maintainability. The ability of an IT infrastructure ponent to be retained in, or restored to, an operational state. Operating level agreement. An internal agreement covering the delivery of services that support the IT service provider in the delivery of services. Risk Management. The identification, selection, and implementation of countermeasures applied toward the identified risks to assets, so that the risks are reduced to an acceptable level. Service Management Function 7 Reliability. The absence of service failure and ponent failure over a given period of time. Serviceability. The contractual arrangements made with thirdparty IT service providers to provided or maintain IT services or ponents. Service level agreement. Written agreement between a service provider and the customer(s) that documents agreed service levels for a service. Service outages. See downtime. 4 Processes and Activities This chapter provides a detailed discussion of the processes and activities that occur in the Availability Management SMF. Process Flow Summary The Availability Management SMF consists of three main processes and a number of subprocesses as follows:  Define service level requirements  Define critical customer functions  Define availability requirements  Propose availability solution  Identify major information technology service ponents  Design for availability  Define availability risks and countermeasures  Define lifecycle management needs  Design for recovery  Define incident life cycle  Design for customer satisfaction during outages  Define management processes  Formalize operating level agreements 10 A vailability Management Figure 1 illustrates the process of availability management. Figure 1. Availability management process flow Define Service Level Requirements The terms availability and “high availability” can have very different meanings depending on the context in which they are used and the audience involved. They can be used to describe a wide range of business goals and technical requirements—from relatively easily achieved, hardwareonly availability targets, to very demanding missioncritical targets applying to the availability of the IT service as a whole. As a result, it is relatively easy for inappropriate expectations to be set concerning availability targets. It is also easy for the customer munity to demand higher levels of availability than they are actually willing to pay for once the cost implications are understood. Availability management needs to start with carefully agreeing to availability targets with the customer and determining the cost of downtime or unavailability of the IT service in question so that a realistic IT budget can be established. This process involves an element of education and negotiation on both sides because the customer needs to understand how to define and articulate availability requirements. The IT anization needs to understand the different customer functions that make up the overall IT service and which of these functions are the most critical. The overall task of negotiating service level objects is defined in the service level management process. A brief overview of the process is presented here to provide a background. For more information, see the MOF Service Level Management Service Management Function guide. Service Management Function 11 Define Critical Customer Functions Any given IT service often contains multiple customer functions or transactions, and some of these will have varying availability requirements and impacts on the business if they fail. Each of the major business functions or transactions that make up the overall IT service needs to be identified and ranked in order of importance with the most critical elements being singled out for particular attention. Interdependencies between services and any reliance on lessimportant services also need to be identified. For example, a new critical callhandling system may rely heavily on file and print services being provided from elsewhere within the IT infrastructure, and this may require the criticality of the file and print s。