Draft Document for Review April 7, 2004 6:15 pm

6947ch07.fm

IRD addresses three separate but mutually supportive functions:

￿LPAR CPU management

WLM dynamically adjusts the number of logical processors within a logical partition and the processor weight based on the WLM policy. The ability to move the CPU weights across an LPAR cluster provides processing power to where it is most needed based on WLM goal mode policy.

￿Dynamic channel path management (DCM)

DCM moves channel bandwidth between disk control units to address current processing needs. The z990 supports DCM within a Logical Channel Subsystem.

￿Channel Subsystem Priority Queuing

This feature on the zSeries allows the priority queueing of I/O requests in the Channel Subsystem and the specification of relative priority among logical partitions. WLM in goal mode sets the priority for a logical partition and coordinates this activity among clustered logical partitions.

7.5.1LPAR CPU management

LPAR CPU management allows WLM working in goal mode to manage the processor weighting and logical processors across an LPAR cluster.

LPAR CPU management was enhanced in z/OS 1.2 to dynamically manages non-z/OS operating systems such as Linux and z/VM. This function allows z/OS WLM to manage the CPU resources given to these partitions based on their relative importance compared to the other workloads running in the same LPAR cluster.

Note: In order to manage non-z/OS images, such as Linux, z/VM, VM/ESA, TPF, z/VSE or VSE/ESA, at least one image in the LPAR Cluster must be running z/OS 1.2 or higher.

Workload Manager distributes processor resources across an LPAR cluster by dynamically adjusting the LPAR weights in response to changes in the workload requirements. When important work is not meeting its goals, WLM will raise the weight of the partition where that work is running, thereby giving it more processing power. As the LPAR weights change, the number of online logical CPUs may also be changed to maintain the closest match between logical CPU speed and physical CPU speed.

LPAR CPU management runs on a zSeries server in z/Architecture mode, and in LPAR mode only. The participating z/OS system images must be running in goal mode. It also requires a CF level 9 or above Coupling Facility structure.

Enabling LPAR CPU management involves defining the Coupling Facility structure and then performing several operations on the hardware management console: defining logical CPs, and setting initial, minimum, and maximum processing weights for each logical partition.

CPU resources are automatically moved toward logical partitions with the most need by adjusting the partition’s weight. The sum of the weights for the participants in an LPAR cluster is viewed as a pooled resource that can be apportioned among the participants to meet the goal mode policies. The installation can place limits on the processor weight value.

WLM will also manage the available processors by varying off unneeded CPs (more logical CPs implies more parallelism, and less weight per CP).

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IBM 990 manual Lpar CPU management
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990 specifications

The IBM 990 series, often referred to in the context of IBM's pioneering efforts in the realm of mainframe computing, represents a unique chapter in the history of information technology. Introduced in the late 1960s, the IBM 990 series was designed as a powerful tool for enterprise-level data processing and scientific calculations, showcasing the company's commitment to advancing computing capabilities.

One of the main features of the IBM 990 was its architecture, which was built to support a wide range of applications, from business processing to complex scientific computations. The system employed a 32-bit word length, which was advanced for its time, allowing for more flexible and efficient data handling. CPUs in the IBM 990 series supported multiple instructions per cycle, which contributed significantly to the overall efficiency and processing power of the machines.

The technology behind the IBM 990 was also notable for its use of solid-state technology. This provided a shift away from vacuum tube systems that were prevalent in earlier computing systems, enhancing the reliability and longevity of the hardware. The IBM 990 series utilized core memory, which was faster and more reliable than the magnetic drum memory systems that had been standard up to that point.

Another defining characteristic of the IBM 990 was its extensibility. Organizations could configure the machine to suit their specific needs by adding memory, storage, and peripheral devices as required. This modular approach facilitated the growth of systems alongside the technological and operational demands of the business environments they served.

In terms of software, the IBM 990 series was compatible with a variety of operating systems and programming environments, including FORTRAN and COBOL, enabling users to access a broader array of applications. This versatility was a significant advantage, making the IBM 990 an appealing choice for educational institutions, research facilities, and enterprises alike.

Moreover, the IBM 990 was engineered to support multiprocessing, which allowed multiple processes to run simultaneously, further increasing its effectiveness in tackling complex computing tasks.

In summary, the IBM 990 series represents a significant advancement in computing technology during the late 20th century. With a robust architecture, versatile configuration options, and a focus on solid-state technology, the IBM 990 facilitated substantial improvements in data processing capabilities, making it a cornerstone for many businesses and academic institutions of its time. Its impact can still be seen today in the continued evolution of mainframe computing.
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