More efficient high availability and resource utilization through manageability

8
HP-UX Workload Manager features that support
HP Serviceguard
WLM has several features that simplify integration with Serviceguard and create a more efficient
high-availability solution. These features include:
• condition statement in SLO definitions—Using a condition statement, you can enable or
disable an SLO based on:
– Time
– Day
– Date
– Some event on the system, such as the activation or deactivation of a Serviceguard package
– Metric value
• Serviceguard package active command—WLM has a command named sg
_pkg_active that
notifies WLM (once per WLM interval) when a package is activated or deactivated.
• transient
_groups tunable (available starting with WLM A.02.01)—By their nature, WLM
workload groups for Serviceguard packages are often waiting, with no active SLOs, for packages
to fail over. By default, a workload group with no active SLOs is still allocated minimum system
resources. By setting the transient
_groups tunable, you instruct WLM to remove workload
groups with no active SLOs, freeing the resources for more productive use.
• extended_shares tunable (available starting with WLM A.03.01)— By setting the
extended_shares tunable, you instruct WLM to provide smaller minimum allocations to groups
with inactive SLOs. Instead of 1% of CPU (or memory), the groups are allocated 0.2%. Granularity
for minimum allocations are based on 0.1% increases (for example, 0.3%, 0.4%, 0.5%). With
extended_shares enabled, WLM can support a maximum of 256 groups instead of 64 (support of
this new maximum starts with HP-UX 11i V2 Update 2). Use this tunable instead of the
transient_groups tunable to ensure that groups are not removed when their SLOs are inactive
but are instead provided smaller minimum allocations. The extended_shares tunable requires
that you use absolute CPU units (set the absolute_cpu_units tunable to 1, causing CPU
allocations to be based on 1000 shares instead of 100).
For information on using these features, see the “Configuring HP-UX Workload Manager” section.
You can simplify the use of these features by using the WLM configuration wizard.
Configuring HP Serviceguard
Integrating WLM with Serviceguard requires no additional Serviceguard configuration and can even
simplify your failover scripts. With WLM managing resource allocation among the packages, your
failover scripts will no longer have to shut down low-priority packages when high-priority packages
fail over.
Configuring HP-UX Workload Manager
One approach for using WLM with Serviceguard is to create a single WLM configuration that you use
on each node in the Serviceguard cluster. This one WLM configuration creates WLM workload
groups for each Serviceguard package in the cluster. Then, whenever any package fails over to any
node in the cluster, it has a workload group waiting for it. However, that group has active SLOs only