The gWLM Management Model

gWLM is designed to support utility computing across a data center by providing resource-sharing policies that you centrally create and monitor. gWLM moves resources among the workloads in a shared resource domain (SRD) as needed—based on the policies you specify.

gWLM allows you to manage resource allocations for several types of system divisions, discussed below. These divisions are referred to as compartments in gWLM.

HP-UX Hardware Partitions (npar)
A hardware partition, also known as an nPartition or npar, is a physical partition of a server, where each npar runs its own instance of the HP-UX operating system.
Using the HP Instant Capacity product, gWLM simulates the movement of CPUs among npars by turning off an active CPU in one npar then turning on a deactivated CPU in another npar in the same complex. Thus, the first npar has one less active CPU, while the second npar has one additional active CPU. (gWLM maintains the number of active CPUs, honoring the Instant Capacity usage rights. As a result, no additional costs are incurred.)
HP-UX Virtual Partitions (vpar)
A virtual partition is a software partition of a server or of a single nPartition, where each virtual partition runs its own instance of the HP-UX operating system. A virtual partition cannot span an nPartition boundary.
HP Integrity Virtual Machines (hpvm)
Virtual machines are a robust soft-partitioning and virtualization technology that provides operating system isolation, with sub-CPU allocation granularity and shared I/O.
Processor sets (psets)
A processor set is a collection of processors (CPUs) grouped together for the exclusive access by applications assigned to that processor set. Each application runs only on processors in its assigned processor set.
Compartments based on psets are available on HP-UX and Linux. (On Linux, gWLM simulates psets using CPU affinity masks.)
HP-UX Fair Share Scheduler groups (fss groups)
A group of processes that has its CPU allocation managed by the Fair Share Scheduler that is available with HP-UX. A benefit of fss groups is their granularity: You can allocate fractions of CPU resources, rather than only whole CPUs, to the group of processes.

For additional information on these partitions, visit:

HP Virtual Server Environment web site:
http://www.hp.com/go/vse
The “Technical Documentation website for HP Virtual Server Environment (VSE)” web site:
http://docs.hp.com/en/hplex.html
The “Global Workload Manager” topic and the glossary in the online help for gWLM

As noted above, gWLM can manage workloads on both HP-UX and Linux.

gWLM manages resources based on the following model:

You decide which of your systems you want to manage and what type of compartment you want to use. (For psets and fss groups, gWLM creates the compartments for you.)
You assign each workload to a compartment.
You associate a policy to the workload indicating how gWLM should allocate resources to the workload’s compartment. (gWLM comes with several policies and also lets you define your own. You can use a single policy for multiple workloads, minimizing the number of policies if desired.)
gWLM monitors the CPU consumption of all the workloads in the SRD during the current allocation interval.
At the end of the interval, gWLM adjusts the CPU allocations for the compartments in accordance with the policies.
gWLM repeats the previous two steps.

For information on what types of workloads to combine for optimal resource utilization, refer to the online help topic “Getting the Most Out of gWLM,” available in gWLM’s graphical interface in SIM.

The gWLM Management Model

Technical documentation

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