6947ch07.fm

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

Within an LPAR cluster, the prioritization is managed by WLM goal mode and coordinated across the cluster. Hence the range should be set identically for all logical partitions in the same LPAR cluster.

WLM sets priorities within a range of eight values that will be mapped to the specified range. If a larger range is specified, WLM uses the top eight values. If a smaller range is specified, WLM maps its values into the smaller range, retaining as much function as possible within the allowed range. Note that the WLM calculated priority is still a range of 8. The mapped priority is shown in Table 7-5 on page 182.

A range of eight values is recommended for CSS I/O priority-capable logical partitions. If the logical partition is run in compatibility mode or with I/O priority management disabled, the I/O priority is set to the middle of the specified range.

Table 7-5 WLM CSS priority range mapping with specified range less than 8

WLM CSS priorities

Calculated

Specified

(6)

(5)

(4)

(3)

(2)

(range width)

range (8)

range (7)

 

 

 

 

 

 

 

 

 

 

 

 

 

System work

FF

FF

FF

FF

FF

FF

FF

 

 

 

 

 

 

 

 

Importance 1&2 missing goals

FE

FE

FE

FE

FE

FE

FF

 

 

 

 

 

 

 

 

Importance 3&4 missing goals

FD

FE

FE

FE

FE

FE

FF

 

 

 

 

 

 

 

 

Meeting goals. Adjust by ratio of

FC-F9

FD-FA

FD-FB

FD-FC

FD

FE

FF

connect time to elapsed time.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Discretionary

F8

F9

FA

FB

FC

FD

FE

 

 

 

 

 

 

 

 

7.5.5 Special considerations and restrictions

Unique LPAR cluster names

LPAR clusters, running on a 2064, 2066, 2084, or 2086 server, must be uniquely named. This is the sysplex name that is associated with the LPAR cluster. Managed channels have an affinity (are owned by) a specific LPAR cluster. Non-unique naming creates problems in terms of scope of control.

Disabling Dynamic Channel Path Management

To disable Dynamic Channel Path Management within an LPAR cluster running z/OS, turning off the function by using the SETIOS DCM=OFF command is not sufficient. Although a necessary step, this does not ensure that the existing configuration is adequate to handle your workload needs, since it leaves the configuration in the state it was at the time the function was disabled. During your migration to DCM, we would recommend that you continue to maintain your old IODF until you are comfortable with DCM. This will allow you to back out of DCM by activating a known configuration.

Automatic I/O interface reset

When going through all of the steps to enable Dynamic Channel Path Management, also ensure that the “Automatic input/output (I/O) interface reset” option is enabled on the Hardware Management Console. This will allow Dynamic Channel Path Management to continue functioning in the event that one participating system image fails.

This is done by enabling the option in the reset profile used to activate the server. Using the “Customize/Delete Activation Profiles task” available from the “Operational Customization tasks list,” open the appropriate reset profile and then open the Options page to enable the option.

182IBM eServer zSeries 990 Technical Guide

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IBM 990 Special considerations and restrictions, Unique Lpar cluster names, Disabling Dynamic Channel Path Management
Page 195 Page 197

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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