Managing HP Serviceguard for Linux Ninth Edition, April 2009
• If you use the reserved CAPACITY_NAME package_limit, then this is the only
type of capacity and weight you can define in this cluster.
• If you use the reserved CAPACITY_NAME package_limit, the default weight
for all packages is 1. You can override this default in the package configuration file,
via the weight_name and weight_value parameters, as in the example above.
(The default weight remains 1 for any package to which you do not explicitly
assign a different weight in the package configuration file.)
• If you use the reserved CAPACITY_NAME package_limit, weight_name, if used,
must also be package_limit.
• You do not have to define a capacity for every node; if you don't, the node is
assumed to have unlimited capacity and will be able to run any number of eligible
packages at the same time.
• If you want to define only a single capacity, but you want the default weight to
be zero rather than 1, do not use the reserved name package_limit. Use another
name (for example resource_quantity) and follow the Comprehensive Method.
This is also a good idea if you think you may want to use more than one capacity
in the future.
To learn more about configuring weights and capacities, see the documents listed under
For More Information (page 136).
Comprehensive Method
Use this method if the Simple Method (page 129) does not meet your needs. (Make sure
you have read that section before you proceed.) The comprehensive method works
best if packages consume differing amounts of computing resources, so that simple
one-to-one comparisons between packages are not useful.
IMPORTANT: You cannot combine the two methods. If you use the reserved capacity
package_limit for any node, Serviceguard will not allow you to define any other
type of capacity and weight in this cluster; so you are restricted to the Simple Method
in that case.
Defining Capacities
Begin by deciding what capacities you want to define; you can define up to four different
capacities for the cluster.
You may want to choose names that have common-sense meanings, such as “processor”,
“memory”, or “IO”, to identify the capacities, but you do not have to do so. In fact it
could be misleading to identify single resources, such as “processor”, if packages really
contend for sets of interacting resources that are hard to characterize with a single
name. In any case, the real-world meanings of the names you assign to node capacities
and package weights are outside the scope of Serviceguard. Serviceguard simply
Package Configuration Planning 131