Server Tuning on HP-UX

Executive summary
Kernel tunables are kernel configuration variables that allow the operating system to be configured to
fit specific system needs, resulting in better performance and/or more efficient allocation of resources.
The default parameter settings provide reasonable performance but the optimal values may depend
on a system’s hardware configuration and the mix of applications that the system runs.
The Server-Tunables product sets kernel tunables to values appropriate for major customer
business application workloads such as Oracle RDBMS and SAP R/3. Installing and running the
Server-Tunables product will provide a jump-start towards optimal performance for business
applications. The Server-Tunables product is a component of the Tune-N-Tools bundle.
Where to start tuning for performance?
HP-UX 11iv3 provides 184 configurable kernel parameters. Additionally, HP-UX 11i v3 has 139
private parameters which are not visible to the customer as long these have the default value. In
general, kernel parameter default values are dependent on the physical size of the system, the best
knowledge of the development engineer, and are set at the time of the cold install of HP-UX.
Therefore, the kernel parameter default values are not necessarily set to be optimal for a specific
workload. However, to reach higher system performance HP-UX allows the customer to optimize
kernel parameters for a specific workload and to have kernel parameters set to meet the ISV
requirements. To tune or customize the system is a time consuming process for the customer.
The Server-Tunables product saves the customer the effort of doing the first level of performance
tuning. In one simple operation the most important kernel parameters are set to an appropriate level
for major applications on server-class systems. Some application products have specific requirements
for parameter settings and the Server-Tunables product will meet those minimum requirements. In
some cases additional, incremental, performance improvements may be made by additional changes
to kernel tunables but the performance improvements achieved with the Server-Tunables product will
usually be significant.
Who should install the Server-Tunables product?
The Server-Tunables product is designed to permit the installation and operation of major ISVs such as
Oracle and SAP and to improve the system performance of servers running such workloads. The
change to the tunable values is primarily to increase system limits consistent with larger systems. The
product contains scripts that interrogate the system configuration and set the tunable variables in a
manner consistent with the system size. Therefore, it is safe to install the Server-Tunables product on
any size system.
Performance improvements from the installation and running of the Server-Tunables product will be
most significant on server-class systems running workloads such as database servers and application
servers. Smaller systems and systems running different workloads may experience less performance
improvement.
What tunable values are changed?
Each version of the Server-Tunables product will potentially modify a different set of tunables and will
set them to different values than other versions. Each version of the Server-Tunables script may base
the tunable values on different system configuration characteristics and may take into account the
version of the operating system running on the system.
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