HP-UX SNAplus2 R7 Administration Guide

Appendix DUsing SNAplus2 in a High Availability Environment
program. Many software and hardware components deliver SNA network connectivity to the end user in this picture.
Since the HP 9000 server plays such a critical role in maintaining the network connectivity for multiple end users,
it is important to minimize the impact of component failures in and around the server.
For example, consider the following component failures:
• The LAN between the client and the server systems
• The LAN adapter card on the server system
• The LAN networking software on the server system
• The SNAplus2 Link software on the server system
• The operating system on the server system
• Disk drives attached to the server system
• The SNA network adapter card on the server system
• The SNA network between the HP 9000 and the IBM Front End Processor
Other failures to consider include power failures, IBM mainframe outages, client system failures, etc. This
appendix focuses on what can be done to reduce the impact of failures in and around the HP 9000 server system.
Specifically, it discusses the high availability features built into SNAplus2 and how those features can be enhanced
and complemented with the use of HP’s MC/ServiceGuard product.
D.2 SNAplus2 High Availability Features
SNAplus2 already has high availability features built in, namely, LU pools, and client/server configurations.
D.2.1 LU Pools for 3270, 3179G, and LUA
One of the most significant fault-tolerant features of SNAplus2 is the LU Pool feature. This feature allows users
of 3270, 3179G, and LUA to access a pool of LUs rather than a specific LU. Configuration is simpler because you
do not need to know the exact LU name to use. Instead, SNAplus2 allocates an available LU.
The biggest benefit is that the LU pool is made up of LUs from separate SNAplus2 LSs spanning multiple servers.
This type of configuration vastly reduces the number of single points of failure by making the LUs highly avail-
able. A diagram of the LU pool concept will help explain its usefulness.
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