Intel AS/400 RISC Server, 170 Servers, 7xx Servers manual Logical Partitioning on a Dedicated Server

Similar to previous DSD performance behavior for interactive processing, the Interactive CPW rating of 0 allows for system administrative functions to be performed by a single interactive user. In practice, a single interactive user will be able to perform necessary administrative functions without constraint. If multiple interactive users are simultaneously active on the DSD, the Interactive CPW capacity will likely be exceeded and the response times of those users may significantly lengthen. Even though the Interactive CPW capacity may be temporarily exceeded and the interactive users experience increased response times, other processing on the system will not be impacted. Interactive processing on the 270 and 820 DSD models can be tracked using the Management Central function of Operations Navigator.

Logical Partitioning on a Dedicated Server

With V5R1, iSeries logical partitioning is supported on both the Model 270 and Model 820. Just to be clear, iSeries logical partitioning is different from running multiple Domino partitions (servers). It is not necessary to use iSeries logical partitioning in order to be able to run multiple Domino servers on an iSeries system. iSeries logical partitioning lets you run multiple independent servers, each with its own processor, memory, and disk resources within a single symmetric multiprocessing iSeries. It also provides special capabilities such as having multiple versions of OS/400, multiple versions of Domino, different system names, languages, and time zone settings. For additional information on logical partitioning on the iSeries please refer to Chapter 18. Logical Partitioning (LPAR) and LPAR web at: http://www.ibm.com/eserver/iseries/lpar .

When you use logical partitioning with a Dedicated Server, the DSD CPU processing guidelines are pro-rated for each logical partition based on how you divide up the CPU capability. For example, suppose you use iSeries logical partitioning to create two logical partitions, and specify that each logical partition should receive 50% of the CPU resource. From a DSD perspective, each logical partition runs independently from the other, so you will need to have Domino-based processing in each logical partition in order for non-Domino work to be treated as complementary processing. Other DSD processing requirements such as the 15% DB2 processing guidelines and the 15% non-Domino processing guideline will be divided between the logical partitions based on how the CPU was allocated to the logical partitions. In our example above with 50% of the CPU in each logical partition, the DB2 database guideline will be 7.5% CPU for each logical partition. Keep in mind that WRKSYSSTS and other tools show utilization only for the logical partition they are running in; so in our example of a partition that has been allocated 50% of the processor resource, a 7.5% system-wide load will be shown as 15% within that logical partition. The non-Domino processing guideline would be divided in a similar manner as the DB2 database guideline.

Running Linux on a Dedicated Server

As with other iSeries servers, to run Linux on a DSD it is necessary to use logical partitioning. Because Linux is it’s own unique operating environment and is not part of OS/400, Linux needs to have its own logical partition of system resources, separate from OS/400. The iSeries Hypervisor allows each partition to operate independently. When using logical partitioning on iSeries, the first logical partition, the primary partition, must be configured to run OS/400. For more information on running Linux on iSeries, please refer to Chapter 13. iSeries Linux Performance and Linux for iSeries web site at: Http://www.ibm.com/eserver/iseries/linux .

Running Linux in a DSD logical partition will exhibit different performance characteristics than running OS/400 in a DSD logical partition. As described in the section above, when running OS/400 in a DSD logical partition, the DSD capacities such as the 15% DB2 processing guideline and the 15% non-Domino processing guidelines are divided proportionately between the logical partitions based on how the processor resources were allocated to the logical partitions. However, for Linux logical partitions, the DSD guidelines are relaxed, and the Linux logical partition is able to use all of the resources allocated to it outside the normal guidelines for DSD processing. This means that it is not necessary to have Domino

IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
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