HP Serviceguard manual About External Scripts, Example

decide which package to start if it cannot start them both because there is not enough node capacity to support their weight.

Example 1

•pkg1 is configured to run on nodes turkey and griffon. It has a weight of 1 and a priority of 10. It is down and has switching disabled.

•pkg2 is configured to run on nodes turkey and griffon. It has a weight of 1 and a priority of 20. It is running on node turkey and has switching enabled.

•turkey and griffon can run one package each (package_limit is set to 1).

If you enable switching for pkg1, Serviceguard will halt the lower-priority pkg2 on turkey. It will then start pkg1 on turkey and restart pkg2 on griffon.

If neither pkg1 nor pkg2 had priority, pkg2 would continue running on turkey and pkg1 would run on griffon.

Example 2

•pkg1 is configured to run on nodes turkey and griffon. It has a weight of 1 and a priority of 10. It is running on node turkey and has switching enabled.

•pkg2 is configured to run on nodes turkey and griffon. It has a weight of 1 and a priority of 20. It is running on node turkey and has switching enabled.

•pkg3 is configured to run on nodes turkey and griffon. It has a weight of 1 and a priority of 30. It is down and has switching disabled.

•pkg3 has a same_node dependency on pkg2

•turkey and griffon can run two packages each (package_limit is set to 2).

If you enable switching for pkg3, it will stay down because pkg2, the package it depends on, is running on node turkey, which is already running two packages (its capacity limit). pkg3 has a lower priority than pkg2, so it cannot drag it to griffon where they both can run.

About External Scripts

The package configuration template for modular scripts explicitly provides for external scripts. These replace the CUSTOMER DEFINED FUNCTIONS in legacy scripts, and can be run either:

•On package startup and shutdown, as essentially the first and last functions the package performs. These scripts are invoked by means of the parameter external_pre_script (page 252); or

•During package execution, after volume-groups and file systems are activated, and IP addresses are assigned, and before the service and resource functions are executed; and again, in the reverse order, on package shutdown. These scripts are invoked by external_script (page 252).

The scripts are also run when the package is validated by cmcheckconf and cmapplyconf, and must have an entry point for validation; see below.

A package can make use of both kinds of script, and can launch more than one of each kind; in that case the scripts will be executed in the order they are listed in the package configuration file (and in the reverse order when the package shuts down).

In some cases you can rename or replace an external script while the package that uses it is running; see “Renaming or Replacing an External Script Used by a Running Package” (page 312).

Package Configuration Planning 151