z/OS Operating System

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z/OS�, which is highly secure, scalable, and open, offers high-performance that supports a diverse application execution environment. The tight integration that DB2� has with the System z� architecture and the z/OS environment creates a synergy that allows DB2 to exploit advanced z/OS functions.

The z/OS operating system is based on 64-bit z/Architecture�. The robustness of z/OS powers the most advanced features of the IBM� System z10� and IBM System z9� technology and the IBM eServer� zSeries� 990 (z990), 890 (z890), and servers, enabling you to manage unpredictable business workloads.

DB2 gains a tremendous benefit from z/Architecture. The architecture of DB2 for z/OS takes advantage of the key z/Architecture benefit: 64-bit virtual addressing support. With 64-bit z/Architecture, DB2 gains an immediate scalability benefit

The following z/Architecture features benefit DB2:

64-bit storage

Increased capacity of central memory from 2 GB to 16 exabytes eliminates most storage constraints. 64-bit storage also allows for 16 exabytes of virtual address space, a huge step in the continuing evolution of increased virtual storage. In addition to improving DB2 performance, 64-bit storage improves availability and scalability, and it simplifies storage management.

High-speed communication

HiperSockets� enable high-speed TCP/IP communication across partitions of the same System z server, for example, between Linux� on System z and DB2 for z/OS.

Dynamic workload management

The z/OS Workload Manager (WLM) provides solutions for managing workload distribution, workload balancing, and distributing resources to competing workloads. z/OS workload management is the combined cooperation of various subsystems (CICS�, IMS/ESA�, JES, APPC, TSO/E, z/OS UNIX� System Services, DDF, DB2, LSFM, and Internet Connection Server) with z/OS workload management. The Intelligent Resource Director (IRD) allows you to group logical partitions that are resident on the same physical server, and in the same sysplex, into an LPAR cluster. This gives Workload Manager the ability to manage resources across the entire cluster of logical partitions.

Faster processors

With more powerful, faster processors, such as the System z Integrated Information Processor (zIIP), DB2 achieves higher degrees of query parallelism and higher levels of transaction throughput. The zIIP is designed to improve resource optimization and lower the cost of eligible workloads, enhancing the role of the mainframe as the data hub of the enterprise.

In addition to the benefits of z/Architecture, DB2 takes advantage of many other features of the z/OS operating system:

High security

z/OS and its predecessors have provided robust security for decades. Security features deliver privacy for users, applications, and data, and these features protect the integrity and isolation of running processes. Current security functions have evolved to include comprehensive network and transaction security that operates with many other operating systems. Enhancements to the z/OS Security Server provide improved security options, such as multilevel security. The System z environment offers highly secure cryptographic functions and provides improved Secure Sockets Layer (SSL) performance.

Open software technologies

z/OS supports the latest open software technologies that include Enterprise JavaBeans�, XML, and Unicode.

Cluster technology

The z/OS Parallel Sysplex� provides cluster technology that achieves availability 24 hours a day, 7 days a week. Cluster technology also provides the capability for horizontal growth. Horizontal growth solves the problems of performance overheads and system management issues that you typically encounter when combining multiple machines to access the same database. With horizontal growth, you achieve more scalability; your system can grow beyond the confines of a single machine while your database remains intact.

Solid-state drives

Solid-state drives (SSDs) are more reliable, consume less power, and generate less heat than traditional hard disk drives (HDDs). SSDs can also improve the performance of online transaction processing. SSDs are especially efficient at performing random access requests, and they provide greater throughput than HDDs. Some IBM System Storage� series allow a combination of HDDs and SSDs.

Parallel Access Volume (PAV)

IBM Enterprise Storage Server� (ESS) exploits the Parallel Access Volume and Multiple Allegiance features of z/OS and supports up to 256 I/Os per logical disk volume. A single z/OS host can issue I/Os in parallel to the same logical volume, and different hosts can issue I/Os to a shared volume in parallel.

HyperPAV

HyperPAV is available on some IBM System Storage series. HyperPAV helps applications to achieve equal or greater I/O performance than the original PAV feature, but uses fewer z/OS resources.

Adaptive multi-stream prefetching

Adaptive multi-stream prefetching (AMP) is a sequential prefetching algorithm that resolves cache pollution and prefetch waste for a cache that is shared by multiple sequential request streams. AMP works well to manage caches efficiently across a wide variety of workloads and cache sizes.

MIDAW

The System z environment also supports the Modified Indirect Data Address Word (MIDAW) facility, which is designed to improve channel utilization and throughput, and which can potentially reduce I/O response times.

FICON� channels

These channels offer significant performance benefits for transaction workloads. FICON features, such as a rapid data transfer rate (4 GB per second), also result in faster table scans and improved utility performance.

High performance FICON

High Performance FICON (zHPF) is a new FICON protocol and system I/O architecture which results in improvements for small block transfers to disk using the device independent random access method.

Improved hardware compression

Improved hardware compression has a positive impact on performance. For example, utilities that run against compressed data run faster.