Planning and Configuring HP-UX DCE 2.0

Configuring HP-UX DCE Cells
Integrating DCE Services with HP Serviceguard
Chapter 6 69
the server will provide services. A side effect of this call is that the list of
IP addresses supported by the node is established for use later when
determining the binding vector. When this vector is obtained by a server
main routine and registered in the endpoint map, the endpoint map will
contain entries for every IP address identified earlier during the
rpc_server_use_* call. In addition, should this binding vector be
exported to the name space, the name space entry will also identify every
IP address on the node as providing the service associated with that
entry.
While it is possible to edit the contents of the binding vector before using
it to register endpoints or add entries in the name space, few, if any, DCE
server programs actually edit the binding vector. In addition, the DCE
runtime does not re-determine the list of available IP addresses during
the course of server execution, and, again, DCE servers do not, as a
general rule, go through their initialization sequence a second time. As a
result, for all the DCE core servers and most known application DCE
servers, the IP addresses used by the server are set once during
initialization, including all the IP addresses available on the node. The
addresses do not change once set.
In an HP Serviceguard environment, these characteristics might be
problematic. Suppose a node had several packages running on it, each
based on a DCE service and each with its own IP address. The DCE
servers in each package would not only register endpoints using their
own IP address, but will also include the IP address of all the other
packages configured on the node at the time the server started up. Since
all the DCE core services cache IP addresses and store them in their
internal databases, the result is a potentially large number of invalid
entries, adversely affecting performance, causing the generation of a
large number of misleading log messages, and potentially causing the
failure of the DCE infrastructure. These considerations and their affects
do not preclude the use of HP Serviceguard with DCE by any means;
they do, however, require that system administrators be particularly
careful when planning, configuring, and operating a DCE-HP
Serviceguard installation.
Through an environment variable, the DCE runtime provides the means
to restrict the IP addresses identified by the rpc_server_use_*
routines. Used correctly, this variable can alleviate the adverse effects of
the characteristics noted above.