I/O Connectivity

Channel Subsystem Enhancement

Increased addressing with up to 24k subchannels per channel (port) for the FICON Express features: To help facilitate growth as well as continuing to enable server consolidation, we are now supporting up to 24k subchannels per FICON Express channel (channel path identifier - CHPID). Now you will be able to define more devices per FICON channel, which includes primary, secondary, and alias devices. The maximum number of subchannels across all device types addressable within an LPAR remains at 63.75k for subchannel set 0 and 64k-1 for subchannel sets 1 and higher. This support is exclusive to the zEC12 and the zBC12 and applies to the FICON Express8S, FICON Express8, and FICON Express4 features when defined as CHPID type FC. This is supported by z/OS, z/VM, and Linux on IBM z Systems.

FICON Express8S – for zEnterprise EC12,zEnterprise BC12, zEnterprise 196, and zEnterprise 114

Channel subsystem enhancement for I/O resilience

The IBM zEnterprise EC12 and zEnterprise BC12 channel subsystem incorporates an improved load balancing algorithm designed to provide improved throughput and reduced I/O service times, even when abnormal conditions occur. For example, degraded throughput and response times can be caused by multi-system workload spikes, resource contention in storage area networks (SANs) or across control unit ports, SAN congestion, suboptimal SAN configurations, problems with initializing optics, dynamic fabric routing changes, and destination port congestion.

When such events occur, the channel subsystem is designed to dynamically select channels to optimize performance and minimize imbalances in I/O performance characteristics (such as response time and throughput) across the set of channel paths to each control unit. This is done by exploiting the in-band I/O instrumentation and metrics of the z Systems FICON and zHPF protocols.

This channel subsystem enhancement is exclusive to IBM zEnterprise EC12 and zEnterprise BC12 and is supported on all FICON channels when configured as CHPID type FC. This enhancement is transparent to operating systems.

A new generation for FICON, zHPF, and FCP environments
A new generation of features for the storage area network (SAN) was introduced in support of the Peripheral Component Interconnect Express (PCIe) 8 gigabytes per second (GBps) host bus and the PCIe I/O drawer. These features have been designed to support path length reductions, increased start I/Os, and improved throughout for the High Performance FICON for z Systems (zHPF) protocol and the Fibre Channel Protocol (FCP). With two ports per feature, the FICON Express8S features facilitate purchasing the right number of ports, to help satisfy application requirements and better optimize for redundancy.

FCP channels support T10-DIF for enhanced reliability
Recognizing that high reliability is important to maintaining the availability of business-critical applications, the z Systems Fibre Channel Protocol (FCP) has implemented support of the American National Standards Institute's (ANSI) T10 Data Integrity Field (DIF) standard. in September of 2011. This support is now available for Linux on z Systems environments as well as z/VM for guest exploitation.

An extension to the standard, Data Integrity Extensions (DIX), provides checksum protection from the application layer through the host bus adapter (HBA), where cyclical redundancy checking (CRC) protection is implemented.Data integrity protection fields are generated by the operating system and propagated through the storage area network (SAN). z Systems helps to provide added end-to-end data protection between the operating system and the storage device.

T10-DIF support by the FICON Express8S and FICON Express8 features, when defined as CHPID type FCP, is exclusive to zEC12,zBC12, z196, and z114. Linux on z Systems distribution, SUSE Linux Enterprise Server (SLES)  11 SP2 is supported. Exploitation of the T10-DIF standard is supported by z/VM for guest exploitation and by Linux on z Systems. Exploitation is also required by the storage device. Support is available on the DS8000 with Release 6.3.1.

FICON Express8S for channel consolidation: FICON Express8S may also allow for the consolidation of existing FICON Express, FICON Express2, FICON Express4, or FICON Express8 channels onto fewer FICON Express8S channels while maintaining and enhancing performance. You can carry forward your FICON Express4 10KM LX and FICON Express4 SX features to the zEC12 and zBC12. You can carry forward all your FICON Express4 features to zEnterprise 196 (z196) and zEnterprise 114 (z114). FICON Express and FICON Express2 are not supported on z196 and z114 servers.

To request assistance for ESCON or FICON channel consolidation analysis using the zCP3000 tool, contact your IBM representative. They will assist you with a capacity planning study to estimate the number of FICON channels that can be consolidated onto FICON Express8S.

Your IBM representative can also assist you with ESCON to FICON channel migration or refer to IBM Global Technology Services which offers an ESCON to FICON Migration solution, Offering ID #6948-97D, to help facilitate migration from ESCON to simplify and manage a single physical and operational environment while maximizing green-related savings. 

ESCON statements of general direction

Refer to U.S. Announcement letter 111-121 dated July 12, 2011,
IBM zEnterprise 196 enhancements deliver faster access to data and to U.S.
Announcement letter 111-136 dated July 12, 2011, The IBM zEnterprise 114 - A new dimension in computing.

The IBM zEnterprise 196 (z196) and the IBM zEnterprise 114 (z114) are the last z Systems servers to support ESCON channels: IBM plans not to offer ESCON channels as an orderable feature on z Systems servers that follow the z196 (machine type 2817) and z114 (machine type 2818). In addition, ESCON channels cannot be carried forward on an upgrade to such follow-on servers. This plan applies to channel path identifier (CHPID) types CNC, CTC, CVC, and CBY and to feature numbers 2323 and 2324.

z Systems customers should continue migrating from ESCON to FICON. Alternate solutions are available for connectivity to ESCON devices. IBM Global Technology Services offers an ESCON to FICON Migration solution, Offering ID #6948-97D, to help facilitate migration from ESCON to FICON. This offering should help customers to simplify and manage a single physical and operational environment.

The above statement is a revision to prior statements of general direction regarding support of ESCON channels on z Systems.

Refer to U.S. Announcement letter 110-170 dated July 22, 2010
The IBM z Systems -- A new dimension in computing.

Refer to U.S. Announcement letter 109-230 dated April 28, 2009
IBM z Systems enhancements, continuing to manage risk.

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