HP Serviceguard About Package Weights, Package Weights and Node Capacities, Cmmakepkg 1m manpage

3.Halts packages the failing package depends on, starting with the package this package immediately depends on. The packages are halted only if:

•these are failover packages, and

•the failing package can “drag” these packages to a node on which they can all run. Otherwise the failing package halts and the packages it depends on continue to run

4.Starts the packages the failed package depends on (those halted in step 3, if any).

If the failed package has been able to drag the packages it depends on to the adoptive node, Serviceguard starts them in the reverse of the order it halted them in the previous step (that is, the package that does not depend on any other package is started first).

5.Starts the failed package.

6.Starts the packages that depend on the failed package (those halted in step 1).

For More Information

For more information, see:

•The parameter descriptions for priority (page 238) and dependency_ (page 238), and the corresponding comments in the package configuration template file

•The cmmakepkg (1m) manpage

•The white paper Serviceguard’s Package Dependency Feature, which you can find at http:// www.hp.com/go/hpux-serviceguard-docs

About Package Weights

Package weights and node capacities allow you to restrict the number of packages that can run concurrently on a given node, or, alternatively, to limit the total package “weight” (in terms of resource consumption) that a node can bear.

For example, suppose you have a two-node cluster consisting of a large system and a smaller system. You want all your packages to be able to run on the large system at the same time, but, if the large node fails, you want only the critical packages to run on the smaller system. Package weights allow you to configure Serviceguard to enforce this behavior.

Package Weights and Node Capacities

You define a capacity, or capacities, for a node (in the cluster configuration file), and corresponding weights for packages (in the package configuration file).

Node capacity is consumed by package weights. Serviceguard ensures that the capacity limit you set for a node is never exceeded by the combined weight of packages running on it; if a node's available capacity will be exceeded by a package that wants to run on that node, the package will not run there. This means, for example, that a package cannot fail over to a node if that node does not currently have available capacity for it, even if the node is otherwise eligible to run the package — unless the package that wants to run has sufficient priority to force one of the packages that are currently running to move; see “How Package Weights Interact with Package Priorities and Dependencies” (page 150).

Configuring Weights and Capacities

You can configure multiple capacities for nodes, and multiple corresponding weights for packages, up to four capacity/weight pairs per cluster. This allows you considerable flexibility in managing package use of each node's resources — but it may be more flexibility than you need. For this reason Serviceguard provides two methods for configuring capacities and weights: a simple method and a comprehensive method. The subsections that follow explain each of these methods.

144 Planning and Documenting an HA Cluster