Syslogd availability is important to the logging of both local
and remote messages. The following configuration considerations can
help improve the availability of the z/OS® syslogd
remote logging services:
- Ensure that there is a process in place to restart a z/OS syslogd after a failure that results in
the termination of syslogd. This can be accomplished by placing syslogd
in the AUTOLOG list in the TCP/IP profile. This enables TCP/IP to
initially start the syslogd instance as a started task, and also enables
TCP/IP to monitor whether syslogd has a socket bound to the syslogd
port used for remote message receipt (UDP port 514). This approach
works well for single-stack INET configurations. If multiple TCP/IP
stacks are deployed on a single system (that is, a CINET configuration),
you should not use the AUTOLOG list. Alternatively, an installation
can use any available automated operations software package to automate
the start and restart of syslogd. For more information about the AUTOLOG statement, see z/OS Communications Server: IP Configuration
Reference.
- On MVS™ systems that are not
part of a sysplex and that have TCP/IP stacks with multiple network
interfaces, using a static VIPA address can provide for better availability
characteristics should a specific network interface or network experience
an outage. This involves configuring a static VIPA in the TCP/IP profile
or reusing an existing one. No special configuration of the local
syslogd is needed. However, you should configure the remote syslogd
instances to use the static VIPA address as the destination address
when forwarding messages. This can typically be accomplished by either
specifying the static VIPA as the destination address, or specifying
a host name that maps to the static VIPA in the remote syslogd configuration.
- When the recipient syslogd instance is running in a sysplex environment,
additional availability features are available that should be explored.
For example, you can use a multiple application-instance dynamic VIPA
(DVIPA) to represent the syslogd instance on a given system, and the
remote syslogd instances are configured to use that DVIPA address
as the destination IP address for the messages they forward. In this
configuration, if a failure to the MVS system
or TCP/IP stack on which the syslogd instance is running occurs, the
DVIPA is automatically moved to a predefined backup system that is
currently active. This enables the syslogd instance on that backup
system to begin processing these remote messages in a transparent
manner. In this configuration, using the MVS operations
log (OPERLOG) as the destination provides additional benefits, because
the operations log is implemented as a coupling facility log stream
that any system in the sysplex can access. For additional information
related to static and dynamic VIPAs, see Virtual IP Addressing.