Managing Serviceguard 11th Edition, Version A.11.16, Second Printing June 2004

Understanding Serviceguard Software Components
How the Package Manager Works
Chapter 3 81
On Combining Failover and Failback Policies
Combining a FAILOVER_POLICY of MIN_PACKAGE_NODE with a
FAILBACK_POLICY of AUTOMATIC can result in a package’s running on a
node where you did not expect it to run, since the node running the
fewest packages will probably not be the same host every time a failover
occurs.
Using Older Package Configuration Files
If you are using package configuration files that were generated using a
previous version of Serviceguard, then the FAILOVER_POLICY will be the
default package behavior of CONFIGURED_NODE and the
FAILBACK_POLICY will be the default package behavior of MANUAL. If you
wish to change these policies, edit the package configuration file to add
the parameters, or use cmmakepkg to create a new package
configuration file.
Starting with the A.11.12 version of Serviceguard, the
PKG_SWITCHING_ENABLED parameter was renamed AUTO_RUN, and the
NET_SWITCHING_ENABLED parameter was renamed to
LOCAL_LAN_FAILOVER_ALLOWED. The older names will still work in your
configuration files, but it is recommended to change the keywords.
Using the Event Monitoring Service
Basic package resources include cluster nodes, LAN interfaces, and
services, which are the individual processes within an application. All of
these are monitored by ServiceGuard directly. In addition, you can use
the Event Monitoring Service registry through which add-on monitors
can be configured. This registry allows other software components to
supply monitoring of their resources for ServiceGuard. Monitors
currently supplied with other software products include EMS High
Availability Monitors, and an ATM monitor.
If a registered resource is configured in a package, the package manager
calls the resource registrar to launch an external monitor for the
resource. Resources can be configured to start up either at the time the
node enters the cluster or at the end of package startup. The monitor
then sends messages back to ServiceGuard, which checks to see whether
the resource is available before starting the package. In addition, the
package manager can fail the package to another node or take other
action if the resource becomes unavailable after the package starts.