6947ch01.fm Draft Document for Review April 7, 2004 6:15 pm
22 IBM eServer zSeries 990 Technical Guide
1.3.17 Summary
On a physical resource level, z990 is a S/390 architecture server with a maximum of 48 PUs
and 256 GBytes of main memory structured in a four-book configuration. The books are
interconnected by a high speed memory coherence ring, thus building a large and very
efficient SMP. The I/O adapters are housed in three I/O cages, and provide a maximum of
1024 (maximum 256 per LCSS) channel ports.
The z900 to z990 is a “Frame Roll” MES. The z990 A and Z frames are shorter and deeper
than z900's frames, actually taking up less space than the z900. The z900 I/O cards, 16-port
ESCON, FICON Express, PCICA and OSA Express, will move to different I/O slots in the new
z990 system I/O cages.
PR/SM handles these physical resources as one contiguous space and provides, on a logical
level, up to 30 logical partitions and up to four Logical Channel Subsystems with 256 channel
paths each. Thus, a large and scalable physical resource pool is generated, managed by
PR/SM in a highly efficient way, taking advantage of LPAR clustering.
Dynamic CHPID management and I/O priority queuing were introduced with z900. These
capabilities are extended to support Linux (for S/390 and on zSeries) partitions with the same
efficiency. Since the maximum number of supported logical PUs within a partition is 24 (z/OS
V1.6, and z/VM V5.1 plan to have support for up to 24 processors in a single LPAR), multiple
copies of operating systems (z/OS and Linux) run “side-by-side” on the same hardware
platform. z990 also continues to support the latest Ethernet technology, to provide the highest
bandwidth connections to external servers.