Machine type, model and catalog identity
The machine type and model identify the hardware family and chassis. A processor feature identifies a configuration within that family. Keep both with the serial number when requesting a replacement or upgrade; the same short model name can cover different hardware.
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Processor features and activation codes
A processor feature describes the ordered processor configuration. An activation feature enables capacity or a licensed function. A service part identifies replacement hardware. These identifiers serve different jobs, so a matching core count alone does not establish that two items are interchangeable.
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Physical cores, active cores and licensed cores
Physical cores are the processor cores present in the hardware. Active cores are enabled for use. The cores assigned to an IBM i partition and the cores licensed for its software can be smaller counts. A chassis maximum does not establish the capacity of one partition.
S1122 ERGQ 20-core: compare its physical processor arrangement with its IBM i partition limit.
Processor modules, chips and sockets
A socket is the physical processor connection on the system board. A module can contain one chip or more than one chip, depending on the generation and configuration. Add cores only after identifying the number of modules and cores per module. Keep eSCM and DCM arrangements with their exact model.
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Processor clock speed and frequency ranges
Clock speed measures processor cycles per second, normally in GHz. A listed range can describe operating frequencies rather than two different processor orders. Core count and processor generation also affect throughput, so GHz alone cannot size a Power replacement.
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Processor cache per core and per module
Processor cache is fast memory close to the cores. L2 and L3 identify cache levels. A per-core number and a per-chip or per-module total have different scopes; compare the same level and scope before treating a larger number as an upgrade.
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IBM i Commercial Processing Workload: CPW
CPW is IBM’s Commercial Processing Workload rating for comparing IBM i processing capacity. It is a sizing reference rather than a promised application response time. Keep the rating with its processor feature and active-core configuration. A partition-limited rating must remain attached to that partition limit.
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Calculated CPW per core
CPW per core divides a stated CPW rating by the cores that deliver it. It helps compare IBM i capacity where core licensing matters. Dividing a whole-system rating by a partition’s smaller core count gives the wrong answer. Use partition CPW and partition cores together when the model imposes an IBM i cap.
S1122 ERGR four-core: use the configuration’s own CPW and core count for the calculation.
AIX relative performance: rPerf
rPerf estimates commercial processing performance for AIX systems. It is distinct from IBM i CPW. Keep the rating with its complete processor arrangement and threading mode; a published two-socket rating is not a rating for an unrated one-socket configuration.
S1124: compare rated processor arrangements and the cases where no AIX rPerf is published.
Single-thread and simultaneous multithreading ratings
ST means single-thread mode. SMT2, SMT4 and SMT8 describe the number of hardware threads available per core in the specified mode. Threads are not additional physical cores. Compare rPerf figures in the same mode and retain the model’s supported operating-system context.
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System nodes and control units
A system node is a hardware building block in a larger Power configuration. Per-node cores and memory must stay separate from the complete system total. A system control unit provides system-level functions and does not add another compute node simply because it occupies rack space.
Capacity on Demand, static activation and shared pools
Capacity on Demand enables eligible installed resources through the applicable activation arrangement. Static activation and shared-pool entitlements have different roles. A processor feature does not establish which activations transfer with a used system. We check the serial number and entitlement with the requested capacity.
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Interactive capacity on older IBM i systems
Some older iSeries configurations distinguish interactive workload capacity from total processor capacity. An interactive CPW figure or user package is not the same as the system’s total CPW. Keep the processor feature, activation or package identifier with each number when sizing an older system.
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Read a model range as a configuration range
A family table can combine several processor orders and chassis arrangements. Its largest figures do not necessarily coexist in one system. Use the selected configuration’s specifications and the source qualifications on its product page when deciding what can be installed together.
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