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Implementing multiple shared-processor pools on your POWER6 or POWER7 server offers the potential for reductions in software licensing and ongoing support fees. This article provides an introduction on how to configure multiple shared-processor pools for your servers and LPARs and maximize your cost savings.

Traditional Implementations

Let's start with a dedicated-processor server environment as the basis for this discussion. Figure 1 shows a typical layout where the production and development LPARs have been configured on separate servers. Historically, physical separation between production and development environments existed to isolate production from misbehaving development code and to avoid the possibility of human error when making hardware or cabling changes to the development environment.

Each LPAR has been assigned the number of processor cores required to handle its peak workload. Between the two servers, a total of 14 processor cores have been configured. Using dedicated processor cores often results in low overall system utilization, because the processor cores assigned to each LPAR can't be shared with other LPARs. Looking at core-based software licensing, you'd typically have to license eight cores for the database application and six cores for the application servers.

The Shared Processor Pool

Combining the production and development servers into a single server implemented with a shared-processor pool can result in significant hardware savings. This consolidated environment is shown in Figure 2. The shared-processor pool allows processor cores to be moved between LPARs based on workload demands. This improves overall system utilization. The total number of processor cores required has been reduced from 14 to eight. In addition, the number of required OS licenses and on-going support fees will likely be reduced.

Regarding concerns about mixing production and development environments on the same server: The POWER Hypervisor has been proven to provide excellent isolation between LPARs. Therefore, you shouldn't be concerned with misbehaving development applications affecting production applications. In addition, you have granular control over processor-core allocations for each LPAR. The POWER Hypervisor strictly enforces the allocations, which prohibit any LPAR from consuming processor resources beyond its allocation. The concern about possible human errors during hardware and cabling changes for the development environment is greatly reduced when Virtual I/O Servers (VIOS) are implemented. VIOS virtualize both network and storage access for the LPARs. With VIOS, most of the changes for network and storage access can be accomplished through the Hardware Management Console (HMC) without the need to have physical access to the server.

For the shared-processor-pool environment, the dedicated processor-core assignments for each LPAR have been replaced with a corresponding number of virtual processors. Yellow boxes designated with a "v" represent the virtual processors. Many software vendors will base their license core counts on the number of virtual processors assigned to the LPARs running their application. For the example shared-processor-pool configuration, there are a total of eight virtual processors running the database application and six virtual processors running as application servers. Comparing notes with the original dedicated-processor environment, the required number of software licenses hasn't been reduced.

Multiple Shared-Processor Pools

Let's reconfigure the server with multiple shared-processor pools. For this example, the shared-processor pool has been replaced with three separate pools, as shown in Figure 3. Each pool has a unique ID number. Similar LPAR types have been grouped together for each of the pools: VIOS LPARs in pool 0, database LPARs in pool 1 and application server LPARS in pool 2.

Charlie Cler supports customers in a solutions-architect role at Forsythe Technology Inc. He can be reached at

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