IBM z/OS manual MultiChip Module is the technology cornerstone for

Each book can support up to 64 GB of Memory, delivered on two memory cards, and 12 STIs giving a total of 256 GB of memory and 48 STIs on the D32 model. The memory is delivered on 8 GB, 16 GB or 32 GB memory cards which can be purchased in 8 GB increments. The minimum memory is 16 GB. The two memory cards associated with each book must be the same size. Each book has 3 MBAs and each MBA supports 4 STIs.

All books are interconnected with a super-fast bi-direc- tional redundant ring structure which allows the system to be operated and controlled by PR/SM operating in LPAR mode as a symmetrical, memory coherent, multiproces- sor. PR/SM provides the ability to confi gure and operate as many as 30 Logical Partitions which may be assigned processors, memory and I/O resources from any of the available books. The z990 supports LPAR mode only (i.e. basic mode is no longer supported).

The MultiChip Module is the technology cornerstone for

flexible PU deployment in the z990 models. For most models, the ability of the MCM to have inactive PUs allows such features as Capacity Upgrade on Demand (CUoD), Customer Initiated Upgrades (CIU), and the ability to add CPs, ICFs, IFLs, and zAAPs dynamically providing nondis- ruptive upgrade of processing capability. Also, the ability to add CPs lets a z990 with spare PU capacity become a backup for other systems in the enterprise; expanding the z990 system to meet an emergency outage situation. This is called Capacity BackUp (CBU). The greater capacity of the z990 offers customers even more fl exibility for using this feature to backup critical systems in their enterprise.

In order to support the highly scalable multi-book system design the I/O SubSystem has been enhanced by intro- ducing a new Logical Channel SubSystem (LCSS) which provides the capability to install up to 1024 CHPIDs across three I/O cages (256 per operating system image). I/O improvements in the Parallel Sysplex Coupling Link archi- tecture and technology support faster and more effi cient transmission between the Coupling Facility and production systems. HiperSockets™ provides high-speed capability to communicate among virtual servers and Logical Partitions; this is based on high-speed TCP/IP memory speed trans- fers and provides value in allowing applications running in one partition to communicate with applications running in another without dependency on an external network. Industry standard and openness are design objectives for I/O in z990. The improved I/O subsystem is delivering new horizons in I/O capability and has eliminated the 256 limit to I/O attachments for a mainframe.

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