HP HP-UX SNAplus2, Administration Manual, Page: 378 / 398

378 Appendix D
Using SNAplus2 in a High Availability Environment
Using SNAplus2 with MC/ServiceGuard
start the node on the backup server until SNAplus2 recognizes that
the primary server is down. This time period can be lengthy (up to 30
minutes).
Therefore, if the backup server is running SNAplus2, it is safest to
completely stop the SNAplus2 software on the backup server before
issuing the activation commands. The complete command set, then is:
function customer_defined_run_cmds
{
snap stop
snap start
snapadmin init_node
snapadmin start_port, port_name=HAPORT
snapadmin start_ls, ls_name=HALS
}
With these commands specified in your Package Control Script, you will
be able to start an SNAplus2 LS called
HALS
on a backup server when
the primary server fails to keep the LS active. These commands work
best in an SNAplus2 client/server environment where the applications
run on client systems and automatically attempt to reestablish LU-LU
sessions anytime a session outage occurs. For standalone environments,
you will also have to consider how your applications will be impacted by
various failures, including entire server system failures.
I/O Compatibility Constraints
The previous section described how to customize your Package Control
Script for the best level of application transparency. To allow the same
SNAplus2 node, port , and LS to run on multiple systems, it is important
that they have compatible networking hardware. In a client/server
configuration, SNAplus2 uses only one configuration file for all of the
SNAplus2 systems defined to be part of the same logical network. To
have more than one server capable of activating the same node, port and
LS , the SNA networking hardware must be installed and configured
similarly on each system. The requirements are different for each type of
link.
LANS
For 802.3, Token Ring, and FDDI LANs, both servers must have the
same type of LAN card installed. The LAN cards on both systems must
be identified by the same SNAplus2 card number.