Planning and Configuring HP DCE 1.7

Planning and Configuring HP DCE 1.7 5-31
Configuring HP DCE Cells
Integrating DCE Services with MC/ServiceGuard
While the replication mechanisms of the Security Service and the
Naming Service differ in design and implementation, they share this
master-slave approach. Therefore, while both services can be considered
highly available for read operations, they do present a single point of
failure for write operations.
The Time Service, on the other hand, does not present the same level of
vulnerability. Most mission critical installations will configure more than
the minimum necessary time servers with multiple time providers. This
being the case, the loss of a single time server is usually not critical.
Installations should not establish an MC/ServiceGuard configuration for
the purpose of maintaining the Time Service alone.
DCE-based applications can also present a single point of failure, unless
the developers provide for the replication of data and functions between
multiple servers. Since replication is a complicated and complex process,
many application designers may choose to depend on a “fail over”
approach such as MC/ServiceGuard to provide availability, rather than
develop and maintain their own replication mechanisms.
In summary, you only need to use MC/ServiceGuard to increase the
availability of DCE Core Services and DCE-based services that are not
replicated. In the case of the DCE Core services, these are the write
functions provided by the DCE master Security and Naming replicas.
Planning Considerations
In your planning for MC/ServiceGuard, you must consider the following
characteristics of DCE and DCE-based programs:
• The DCE runtime and daemons do not themselves support the
concept of dynamic IP addresses.
• Normal DCE programming practice assumes that all IP addresses on
the host should be used for endpoints for exported services.
The DCE runtime determines the available IP addresses on the node
during the execution of any of the rpc_server_use_* routines. These
routines are used in every DCE server to select the protocols over which
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