Choosing a Policy Type

How do you decide which policy type to use? The table below answers this question for several common use cases. The section following the table helps you decide between using an OwnBorrow policy or a utilization policy.

Table 2-1 Choosing a Policy Type

If...	Use the following type of policy...
You want gWLM to allocate a constant amount of CPU resources to a workload	Fixed
You have your own metric by which you want gWLM to manage a workload	Custom
IT acts as a service provider to business units	OwnBorrow This policy type allows you to set an owned amount of resources, while also giving you control over how workloads borrow and lend resources. gWLM provides a “topborrowers” report and a “resourceaudit” report to help you manage your data center using this model. For more information, refer to gwlmreport(1M).
You have static vpars but you want to move to a model where cores migrate among vpars	OwnBorrow For each vpar, set its number of owned cores to its static number of cores. The vpar gets those owned cores whenever needed.
You have npars but you want to move to a model where CPU resources migrate among npars	OwnBorrow Install the HP Instant Capacity product on each npar. (This software allows gWLM to simulate CPU resource movement among the npars.) For each npar, set its number of owned cores to the number of cores you want the npar to have whenever needed.
You want to tap into a pool of resources taking or giving CPU resources as needed—with possibly no access to resources beyond a minimum request	Utilization
You have a policy that should be in effect only for a certain Serviceguard condition	Conditional Select an existing policy and a default policy and then choose from the possible Serviceguard conditions.

Choosing Between an OwnBorrow Policy and a Utilization Policy

OwnBorrow and utilization policies both allocate resources to a workload based on the workload's use of its current allocation. Both policy types also specify minimum and maximum amounts of resources the workload should get. The difference is OwnBorrow policies have an owned amount of resources. A workload with an OwnBorrow policy can lend other workloads its unused resources--down to its minimum--but always gets its owned resources back whenever needed. Similarly, a workload with a utilization policy can lend resources down to its minimum. However, if this workload needs more than its minimum, it can only get additional resources if unused resources are available. Also, if the workload does not consume its entire minimum allocation, those resources are not available to other workloads. Thus, an OwnBorrow policy can provide greater flexibility in attempting to allocate a workload a certain amount of resources when needed while also lending those resources to other workloads when not needed.

Combining the Different Policy Types

Each workload in an SRD must have a policy. Starting with gWLM A.02.00.00.x, you can use any combination of the policy types within an SRD, as shown in the following table.

Table 2-2 Policy Combinations Allowed Starting with gWLM A.02.x

Policy type	Fixed	Utilization	OwnBorrow	Custom
Fixed	Yes	Yes	Yes	Yes
Utilization	Yes	Yes	Yes	Yes
OwnBorrow	Yes	Yes	Yes	Yes
Custom	Yes	Yes	Yes	Yes

If you are managing systems with earlier gWLM releases, you must follow the policy combinations allowed with those releases. With gWLM versions prior to A.02.00.00.x, combinations of policies within a single SRD were limited to the combinations shown in the table below.

Table 2-3 Policy Combinations Allowed Prior to gWLM A.02.x

Policy type	Fixed	Utilization	OwnBorrow	Custom
Fixed	Yes	Yes	Yes	Yes
Utilization	Yes	Yes	—	Yes
OwnBorrow	Yes	—	Yes	—
Custom	Yes	Yes	—	Yes

Choosing a Policy Type

Technical documentation

» Table of Contents

Choosing Between an OwnBorrow Policy and a Utilization Policy

Combining the Different Policy Types