Availability roadmap

In today's fast-paced Internet environment, it is crucial that your data and applications be available to you when you need them. If your customers cannot access your Web site because your system is down, they may go to your competitors instead.

Availability is the measure of how often your data and applications are ready for you to access when you need them. Different companies have different availability needs. Different systems or different applications within the same company may have different availability needs. The purpose of this topic is to guide you through the world of iSeries™ availability and help you decide which availability tools are right for your business. It is important to note that availability requires detailed planning; these availability tools are only useful if you have implemented them before an outage occurs.

Before you can really start to plan for availability on your system, you should become familiar with basic availability concepts, understand the costs and risk associated with outages, and determine your company's needs for availability. Once you have a basic understanding of availability concepts and know what level of availability you need, you can start to plan for that level of availability on a single system or for multiple systems within a cluster environment.

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• Availability concepts
  Before you can plan for the availability of your system, it is important for you to understand some of the concepts associated with availability.
• Estimate the value of availability
  No one would argue the importance of availability. However, when asked to justify the cost of additional hardware to support improved availability, many people do not know how to build a case.
• Decide what level of availability you need
  After understanding availability at a basic level, it important to assess your individual availability needs. Higher availability is more costly than a lower level availability. You must balance your needs and services with the overall cost of implementing and maintaining these availability solutions.
• Prevent unplanned outages
  One way to approach availability is to try to prevent unplanned outages. You can use these different methods to ensure that your system experiences as little unplanned downtime as possible.
• Shorten unplanned outages
  Unplanned outages do occur, and a key to availability is to ensure that when they do occur you can recover from them as quickly as possible.
• Shorten planned outages
  Planned outages are necessary and are expected; however, because they are planned does not mean they are nondisruptive. Planned outages are often related to system maintenance.
• Availability for multiple systems: Clusters
  For multiple system environments, you can use clusters as a strategy to maintain a high or continuous availability for your systems and applications.
• Data resilience solutions for i5/OS Clusters
  This topic provides an overview of different data resilience technologies that can be used to with i5/OS™ Clusters to enhance high availability in multiple system environments.
• Related information for Availability roadmap
  Several sources relate to Availability roadmap. Use these iSeries manuals, IBM^® Redbooks™ (in PDF format), and Web sites to learn more about high availability, backup and recovery, clusters, and other related topics. You can view or print any of the PDFs.