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z/OS I/O Subsystems: Syllabus

Expanding the Horizons of Mainframe I/O

Today, analysts who are responsible for z/OS I/O subsystems face a changing environment and a variety of new technologies as traditional mainframe environments attempt to exploit new technologies such as FICON Express16S, High Performance FICON for z, EC12 and z13 processors, flash drives, Extended Address Volumes, encryption, multi-site remote copy schemas, and storage tiering.

To respond to these challenges and to exploit these new technologies, it is necessary to understand the underlying purpose and critical features of z/Architecture hardware and software. This 4 day seminar provides a unique opportunity to learn about these significant developments in z/OS I/O Subsystems.

Syllabus updated 15 January 2015.


This seminar is intended for systems programmers, performance analysts, capacity planners, and other systems personnel who are responsible for selecting, configuring, optimizing, or managing z/OS subsystems.


What are the primary building blocks of the z/Architecture? What measurement facilities are available?

zSeries Servers
What are the architectural characteristics of the zSeries servers. How does the EC12 processors expand on the z900 thru z196 architectures?

Basic Queueing Theory
What are the basic queueing concepts that are required for I/O performance analysis?

Enterprise Storage Devices
The characteristics of rotating and flash storage will be examined and the seminar will explore how the technologies can best be employed to address the performance requirements of the enterprise. What are Unrecoverable Errors and why are they important? Specific attention will be placed on the long term trends for reliability, capacity, power consumption, and price.

Virtual or Virtualize
Virtualization is the fundamental building block of contemporary storage subsystems. The basic concepts of virtual memory are reviewed and a simple model is proposed for virtualizing CKD volumes to FBA devices.

Storage Protection Schemas
What storage protection schemas are available for enterprise storage subsystems? Given the increasing statutory and regulatory requirements for data retention, it is imperative to understand the available protection schemas.

Logical Volume Skewing
What is Logical volume skewing and how may it be characterized? What are its influences on cache size?

Caching Concepts
Why is caching a good idea and what caching strategies can maximize the benefits of caching for different reference patterns? What is locality of reference and what is the role of the define extent CCW in cached subsystems?

Tiered Storage Architectures
Contemporary storage subsystem designs incorporate multiple levels of storage devices ranging from SATA to flash. How can allocations be controlled or logical volumes and/or extents be migrated to improve subsystem performance?

FICON Connectivity and Performance
FICON represents the next step in I/O subsystem connectivity. The logical and physical characteristics of FICON connectivity are introduced. Particular emphasis is placed on how FICON addresses ESCON's distance related performance problems and how cascaded FICON directors will simplify GDPS design.

Extended Address Volumes
EAVs offer an elegant solution to historical problems of logical volume management. This section will examine the characteristics of addressing schema employed for EAVs.

High Performance FICON for z
zHPF offers the potential of exploiting the performance advantages of native fibre channel to enhance the performance of FICON connectivity. Emphasis will be placed on understanding how existing channel program structures are encapsulated to reduce channel microprocessor utilization and increase effective data transfer rates.

PAVs, Multiple Allegiances, and HyperPAVs
PAVs and multiple allegiances address the historical problem of UCB serialization. Special emphasis is placed on the development of a back-of-the-envelope model to predict the potential performance benefits of PAVs and HyperPAVs.

Long DISC Time
What causes long DISC times on contemporary storage subsystems? How are the cache-hit ratio and the RMF average DISC time related?

Implications of Logical and Physical Volume Size
Perhaps one of the most common concerns of analysts is the impact of logical and physical volume size on the performance of subsystems. An analysis based on simulation modeling is employed to examine the impacts of logical and physical volume size as we enter the era of EAVs. Emphasis will also be placed on the identification of candidate datasets for flash storage.

Remote Copy Planning
As a result of increased security concerns and regulatory requirements, more installations are considering the implementation of Metro Mirror, Global Mirror, XRC, HRC, or SRDF solutions for real time data replication. What are the characteristics of these solutions and how can installations identify and respond to problem volumes and datasets, distance concerns, and management issues? How can the new GDPS distance limits be exploited to provide enhanced protection?

Tape and Virtual Tape
New physical tape architectures and media encryption offer solutions to application data transfer requirements and the secure encryption of media that is transported beyond the bounds of the data center. Virtual tape subsystems offer potential solutions for the small tape management problem. Emphasis will be placed on a review of the currently available hardware and software solutions.

Logical Control Units
What is a logical control unit? How are they defined?

I/O Configuration Definition
The use of HCD and IOCP to define the physical connectivity of I/O subsystems is discussed in detail. Examples are provided for contemporary DASD subsystems. Particular emphasis is placed on performance impacts of IOP and channel path assignment.

Path Selection
The path initialization process is discussed in detail. Specific emphasis is placed on how the channel subsystem identifies and interrogates the control unit, the role of the logical path table in the control unit, and how the outbound and inbound path selection processes work.

Storage Tiering
Storage tiering offers the opportunity automatically assign volume segments to devices with disparate performance expectations within a subsystem. This approach offers the opportunity to improve performance and reduce cost. The SMS management facilities for tier management under z/OS 2.1 are discussed.

Contemporary Storage Subsystems
A detailed comparative analysis of contemporary storage subsystems for z/OS environments is provided.