Managing HP Serviceguard A.11.20.10 for Linux, December 2012

4.8.10.3 Simple Method
Use this method if you simply want to control the number of packages that can run on a given
node at any given time. This method works best if all the packages consume about the same amount
of computing resources.
If you need to make finer distinctions between packages in terms of their resource consumption,
use the Comprehensive Method (page 117) instead.
To implement the simple method, use the reserved keyword package_limit to define each
node's capacity. In this case, Serviceguard will allow you to define only this single type of capacity,
and corresponding package weight, in this cluster. Defining package weight is optional; for
package_limit it will default to 1 for all packages, unless you change it in the package
configuration file.
4.8.10.3.1 Example 1
For example, to configure a node to run a maximum of ten packages at any one time, make the
following entry under the node's NODE_NAME entry in the cluster configuration file:
NODE_NAME node1
. . .
CAPACITY_NAME package_limit
CAPACITY_VALUE 10
Now all packages will be considered equal in terms of their resource consumption, and this node
will never run more than ten packages at one time. (You can change this behavior if you need to
by modifying the weight for some or all packages, as the next example shows.) Next, define the
CAPACITY_NAME and CAPACITY_VALUE parameters for the remaining nodes, setting
CAPACITY_NAME to package_limit in each case. You may want to set CAPACITY_VALUE to
different values for different nodes. A ten-package capacity might represent the most powerful
node, for example, while the least powerful has a capacity of only two or three.
NOTE: Serviceguard does not require you to define a capacity for each node. If you define the
CAPACITY_NAME and CAPACITY_VALUE parameters for some nodes but not for others, the nodes
for which these parameters are not defined are assumed to have limitless capacity; in this case,
those nodes would be able to run any number of eligible packages at any given time.
If some packages consume more resources than others, you can use the weight_name and
weight_value parameters to override the default value (1) for some or all packages. For example,
suppose you have three packages, pkg1, pkg2, and pkg3. pkg2 is about twice as
resource-intensive as pkg3 which in turn is about one-and-a-half times as resource-intensive as
pkg1. You could represent this in the package configuration files as follows:
• For pkg1:
weight_name package_limit
weight_value 2
• For pkg2:
weight_name package_limit
weight_value 6
• For pkg3:
weight_name package_limit
weight_value 3
Now node1, which has a CAPACITY_VALUE of 10 for the reserved CAPACITY_NAME
package_limit, can run any two of the packages at one time, but not all three. If in addition
116 Planning and Documenting an HA Cluster