HP Serviceguard manual Defining Weights, Defining Default Weights

NOTE: You do not have to define capacities for every node in the cluster. If any capacity is not defined for any node, Serviceguard assumes that node has an infinite amount of that capacity. In our example, not defining capacity A for a given node would automatically mean that node could run pkg1 and pkg2 at the same time no matter what A weights you assign those packages; not defining capacity B would mean the node could run pkg3 and pkg4 at the same time; and not defining either one would mean the node could run all four packages simultaneously.

When you have defined the nodes' capacities, the next step is to configure the package weights; see “Defining Weights”.

Defining Weights

Package weights correspond to node capacities, and for any capacity/weight pair, CAPACITY_NAME and weight_name must be identical.

You define weights for individual packages in the package configuration file, but you can also define a cluster-wide default value for a given weight, and, if you do, this default will specify the weight of all packages that do not explicitly override it in their package configuration file.

NOTE: There is one exception: system multi-node packages cannot have weight, so a cluster-wide default weight does not apply to them.

Defining Default Weights

To pursue the example begun under “Defining Capacities” (page 146), let's assume that all packages other than pkg1 and pkg2 use about the same amount of capacity A, and all packages other than pkg3 and pkg4 use about the same amount of capacity B. You can use the WEIGHT_DEFAULT parameter in the cluster configuration file to set defaults for both weights, as follows.

Example 3

WEIGHT_NAME A

WEIGHT_DEFAULT 20

WEIGHT_NAME B

WEIGHT_DEFAULT 15

This means that any package for which weight A is not defined in its package configuration file will have a weight A of 20, and any package for which weight B is not defined in its package configuration file will have a weight B of 15.

Given the capacities we defined in the cluster configuration file (see “Defining Capacities”), node1 can run any three packages that use the default for both A and B. This would leave 20 units of spare A capacity on this node, and 5 units of spare B capacity.

Defining Weights for Individual Packages

For each capacity you define in the cluster configuration file (see “Defining Capacities”) you have the following choices when it comes to assigning a corresponding weight to a given package:

1.Configure a cluster-wide default weight and let the package use that default.

2.Configure a cluster-wide default weight but override it for this package in its package configuration file.

3.Do not configure a cluster-wide default weight, but assign a weight to this package in its package configuration file.

4.Do not configure a cluster-wide default weight and do not assign a weight for this package in its package configuration file.

148 Planning and Documenting an HA Cluster