Z890 Design and Technology

As with the z990, an improvement to the I/O subsystem has been introduced on the z890 to “break the barrier” of the 256 CHPIDs per Channel Subsystem. Horizontal growth is provided by allowing the deﬁ nition of two Logical Channel SubSystems (LCSSs) each capable of supporting up to 256 CHPIDs, giving a total of 512 CHPIDs per z890 server. The z890 can support up to 30 Logical Partitions (LPARs). There is still a 256 CHPID limit per operating system. (Note: The lowest Capacity Setting 110 can sup- port up to 240 CHPIDs, dependent on channel type, and up to a maximum of 15 LPARs.)

These are some of the signiﬁ cant enhancements in the zSeries 890 server that bring improved performance, avail- ability and function to the platform. The following sections highlight the functions and features of the server.

z890 Design and Technology

The z890 is designed to provide balanced system perfor- mance. From server to the storage to the system’s I/O and network channels, end-to-end bandwidth is provided and designed to deliver data where and when it is needed. The z890 is a scaled down version of the z990 using one of the most advanced chip and packaging technology in the industry. The z890 has more technology similarities to the z990 than the z800 does to the z900. Both the z890 and z990 use the latest MCM packaging and book package.

The z890 compared to the z800 provides a signiﬁ cant increase in system scalability and opportunity for server consolidation by providing improved model granularity while scaling to 2X the performance of the z800. The z890’s processor cycle time has been improved to 1.0 ns from the 1.6 ns of the z800. All z890’s have a single Mul- tiChip Module (MCM) that is nearly identical to the z990’s

MultiChip module. The differences are minor. With fewer functional processors and a slower cycle time less power is required for the z890 MCM enabling air cooling. The air cooled z890 MCM uses approximately 450 Watts compared to the liquid cooled z990 MCM which requires approximately 650 Watts. The z890 MCM can deliver 1 to 4-way conﬁ gurations with a variety of engine sizes. The z890 MCM, which measures approximately 95 x 95 mil- limeters, is about 42% smaller than the z900’s 127 mm

x 127 mm MCM. The z890 MCM contains 5 Processor Unit (PU) chips, four Storage Data (Level 2 cache) chips, a Level 2 Cache Storage Controller chip and two main Memory Storage Controller (MSC) chips which control the main memory or Level 3 storage. The MCM contains 101 glass ceramic layers of which 23 layers are to provide interconnection between the chips and the off-module environment. In total, there are approximately 378 meters of internal copper wiring on both the z890 and z990 MCMs compared to the 997 meters of internal wiring needed

for the MCMs in the z900 190 and 290 models. The new smaller MCM packaging delivers an MCM with many shorter paths. The z890 MCM is 40% smaller than the

z900 MCM. It has over 20% more I/O connections and over a 130% I/O density improvement compared to the z900 MCM.

The z890’s MCM provides support for 5 PUs and 32 MB level 2 cache which can be shared by all PUs. Each PU chip contains approximately 122 million transistors and measures 14.1 mm x 18.9 mm. The design of the MCM technology on the z890 provides the ﬂ exibility to conﬁ g- ure the PUs for different uses. One of the PUs is reserved for use as dedicated I/O Processor (IOP), commonly referred to as a System Assist Processor (SAP) enabling the Central Processor to avoid the burden of I/O set