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 might 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 might have different availability needs. The purpose of this topic is to guide you through the world of System i™ 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 the basic availability concepts, understand the costs and risk associated with outages, and determine your company's needs for availability. After 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 on multiple systems within a cluster environment.
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- Availability concepts
Before you plan for the availability of your system, it is important for you to understand some of the concepts associated with availability.
- Estimating the value of availability
You need to build a business case for improving availability when you are asked to justify the cost of additional hardware to support availability.
- Deciding what level of availability you need
After understanding availability at a basic level, it is 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.
- Preventing 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.
- Shortening unplanned outages
Unplanned outages do occur, and a key to availability is to ensure that you can recover from the outages as quickly as possible.
- Shortening 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 contains 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
Listed here are the product manuals and IBM® Redbooks™ (in PDF format), Web sites, and information center topics that relate to the Availability roadmap topic collection. You can view or print any of the PDFs.