HP-UX SNAplus2 R7 Administration Guide

Appendix DUsing SNAplus2 in a High Availability Environment
In this example, nine LUs are used by APPC production applications that run on the client systems. These LUs are
configured to use an SNAplus2 LS called
HALS. This LS is configured to use the SNAplus2 LAN port HAPORT and
can be run under the SNAplus2 node HANODE. Normally, this configuration is run on the primary server hp_pr
as shown below. In addition, five LUs are used by APPC transaction programs for development purposes. These
LUs are configured to use an SNAplus2 LS called DEVLS. This LS is configured to use the SNAplus2 LAN port
DEVPORT, and can be run under the SNAplus2 node DEVNODE. Normally, this configuration is run on the backup
server hp_back as shown below.
Figure D–4 SNAplus2 on Primary and Backup Servers
Client Client Client Client
3xxx
Communications
Controller
IBM
Host
LAN
Primary HP-UX Server hp_pri
Production Configuration
Node.................HANODE
LS.....................HALS
Port...................HAPORT
LUs...................HALUO1...HALU09
Backup HP-UX Server hp_back
Development Configuration
Node................DEVNODE
LS....................DEVLS
Port..................DEVPORT
LUs..................DEVUO1...DEVLU09
Token Ring
Whenever the primary server is about to become unavailable (during preventative maintenance periods, for exam-
ple), the SNA connectivity is switched to the backup server through the following steps:
1. The SNAplus2 Port HAPORT is started on the backup server using the command snapadmin start_port,
port_name=HAPORT.
2. The SNAplus2 LS HALS is started on the backup server, if it is configured to be operator started, using the
command snapadmin start_ls, ls_name=HALS.
At this point, the backup server has completely taken over the primary server and is providing the
HALU01...HALU09 LUs for the production applications. The less important development LUs are no longer
available. The key point is that the production applications do not need to change when this switch takes place.
The location of where the software components are started changes, not the underlying SNAplus2 configuration.
SNAplus2 will automatically route data to and from the production applications through the backup server.
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