Appendix A Using High Availability Strategies

High availability is the term used to describe computer systems that have been configured so as to minimize the percentage of time that they will be down or otherwise unavailable, and as a result, allow for the greatest degree of usefulness. High system availability is achieved by minimizing the possibility that a hardware failure or a software defect will result in a loss of the use of the system or in a loss of its data. Improved system and data availability can therefore result from advantageous use of either hardware and/or software components which serve to reduce the impact of errors by making use of redundant and isolated components such as dual busses, I/O devices, and duplicate copies of data.

Some of the various means of implementing high availability that should be considered in administering HP-UX systems are reviewed here.

	NOTE: High availability is a complex topic that can only be briefly summarized here. For a more complete technical discussion, please refer to the white paper, Choosing the Right Disk Technology in a High Availability Environment. This document can be found on the HP documentation web site, http://docs.hp.com. Select “High Availability” and then “White Papers.”