Operating Systems

Most data centers today have one of the models of IBM’s System z processor technology. Many customers have been able to take advantage of specialty processors to facilitate their sysplex environments with Integrated Coupling Facilities (ICFs), and consolidate distributed workloads on a mainframe platform with Integrated Facilities for Linux (IFLs). Now, with z9 and z10 processors, there are opportunities to reduce software license costs with System z Integrated Information Processors (zIIPs) and System z Application Assist Processors (zAAPs). This article examines some of the basic concepts of the technology, the considerations for successful implementation, and exploiters of these processors.

Under the zCovers

If we look under the covers of the z10, it looks largely similar to its predecessor, the z9; external physical differences include a slight change in dimensions and the z10 sports a green stripe down its side instead of a blue stripe. Each system is dubbed a “green machine” with new higher frequency, four-core processor chips. The z10 BC chips run at 3.5 GHz, and the z10 EC runs at 4.4 GHz—much faster than the z9. Between the two processors, there are 230 different models at various configurations and processor speeds. With about 28 MIPS up to nearly 31,000 MIPS in a 64- way configuration, there’s a machine model for everyone.

Looking further under the covers, we will find books housing the Multi- Chip Modules (MCMs) (see Figure 1). The MCM contains the processors, storage, and other controls. With the MCM, all the processors are physically identical. It’s the controls on the MCM that “characterize” whether the physical engines are sub-capacity, or if they’re specialty engines, based on what was ordered. Physically, there’s no difference in any of the processors on the MCM. All engines run at the same maximum speed as allowed by the processor model. The characteristics of a particular processor have been defined to act like a full-speed Central Processor (CP), a sub-capacity CP, ICF, IFL, zIIP, or zAAP. All specialty engines always run at full speed.


zIIP or zAAP?

A zIIP is available on z9 and z10 processors. z/OS manages and directs work to the zIIP. z/VM also can emulate or virtualize zIIPs for z/OS guests running under z/VM. Work directed to the zIIP must run as an Enclave Service Request Block (SRB). Current vendor solutions may need re-architecting to take advantage of the zIIP.

A zAAP is available on z890, z990, z9, and z10 processors. z/OS manages and directs work to the zAAP. z/VM also can emulate or virtualize zAAPs for z/OS guests running under z/VM. Work directed to the zAAP must be Java or certain parts of XML parsing. Current vendor solutions don’t need re-architecting to take advantage of the zAAP. Activating a zAAP in the customer environment can have immediate benefit.


zIIPs and zAAPs potentially help sites avoid processor upgrades when current capacity has been exceeded (see Figure 2). Processor upgrades lead to increased software licensing charges. zIIPs and zAAPs aren’t generally a performance opportunity, although transaction throughput could improve in some instances. zIIPs and zAAPs may help facilitate green initiatives such as distributed server consolidation.

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