White Paper Mainframe Unlock the Full Value of Mainframe Technology with a Switched-FICON Architecture Technical and Business Reasons for Implementing a Switched-FICON Architecture Abstract A networked FICON storage architecture for your mainframe is a long-term, well-documented industry best practice. Networked storage architectures beat direct-attached architectures in terms of RAS, performance, scalability, and long-run costs. This paper explores the technical and business reasons for implementing switched-FICON instead of direct-attached storage infrastructures and explores the advantages of Brocade’s FICON SAN product family, which provides an outstanding, industry-leading solution for mainframe environments. Executive Summary Some mainframe organizations might consider implementing an old-style, traditional direct-attached high-performance FICON for IBM Z (zHPF) architecture. However, organizations should ask what they would be giving up by not deploying mainframe over a switched-FICON architecture. Will it actually result in efficiencies and cost savings? With the many enhancements and improvements in mainframe I/O technology in the past 10 years, a frequently asked question is “Do I need FICON switching technology, or should I go with direct-attached storage?” With up to 320 FICON Express16SA channels supported on an IBM z15, why not just direct-attach the control units? The short answer is that with all of the ongoing I/O improvements, switching technology is needed—now more than ever. In fact, there are more reasons to use switched-FICON than there were to use switched-ESCON. Some of these reasons are purely technical; others are more business-related. FICON switching directors provide high availability (architected for 99.999% availability) with redundant components and no single points of failure or repair. You can use modern FICON directors to attach Fibre Channel hosts and devices in addition to FICON hosts and devices. With Fibre Channel and FICON intermix mode, both Fibre Channel Protocol (FCP) and FICON upper-level protocols can be supported within the same director when deployed independently by port. Director ports operate in either Fibre Channel or FICON mode. A total cost of ownership (TCO) analysis focused on the long term will clearly demonstrate that the modern mainframe customer is better off implementing a switched-FICON architecture. Brocade’s unique history of technical development with the IBM Z Systems I/O product team has produced the world’s most advanced mainframe computing and storage systems SAN. Brocade’s technical heritage stretches back to the late 1980s with our creation of channel extension technologies to broaden data centers beyond the “glass house.” Then we revolutionized the classical “computer room” with the invention of the original ESCON SAN of the 1990s, which was leveraged in the 2000s as we facilitated geographically dispersed FICON storage systems. Today, the most compelling innovations to be found in mainframe storage networking technology are the product of the nearly 30-year-long partnership between Brocade and the IBM Z Systems team. Broadcom Mainframe-FICON-WP100 March 27, 2020 Mainframe White Paper Unlock the Full Value of Mainframe Technology with a Switched-FICON Architecture As the flash era of this decade disrupts the traditional mainframe storage networking mind-set, Brocade and IBM have released a series of features and functions that are specifically designed and integrated to address the needs and demands of the data center. These technologies leverage the fundamental capabilities of Brocade switching to enhance the world’s most reliable and crucial systems. Recommendations Direct-attached FICON storage might appear to be an inexpensive way to take advantage of mainframe technology. However, a closer examination will show why a switched-FICON architecture is a better, more robust design for enterprise data centers than direct-attached FICON. There are six key technical reasons for connecting storage control units using switched-FICON: To replace the I/O Operations (I/O Ops) component of System Automation for z/OS, widely known as ESCON Manager, that has been removed and is out of service as of September 2019. To overcome buffer credit limitations on FICON Express 16Gb/s and 8Gb/s channels. To build fan-in, fan-out architecture designs for maximizing resource utilization. To localize failures for improved availability. To increase scalability and enable flexible connectivity for continued growth. To leverage new FICON technologies that are available only when switched-FICON is implemented, such as N_Port ID Virtualization (NPIV), Dynamic Channel Path Management (DCM), and FICON CUP Diagnostics. I/O enhancements to IBM mainframes, such as Dynamic Channel Path Management and IBM Z Discovery and Configuration (zDAC), require a networked storage architecture (utilizing FICON directors) if the end user wishes to take advantage of them. IBM Z offers unprecedented performance, scalability, and innovative features. To take full advantage of IBM Z, the end user must have an equally capable storage array and FICON director platform for connectivity. Our OEM storage partners combined with Brocade Gen 6 are the ideal combination with IBM Z mainframes, whether it is for a traditional z/OS, Linux, Protocol Intermix Mode (PIM), or private cloud environment. You can be assured that Brocade has the experience and that Gen 6 is the best FICON I/O infrastructure in the industry for mainframe data centers. Mainframe users should utilize switched-FICON to provide for the proper deployment of I/O in every IBM Z data center that they operate. It is the only way in which they can derive the full value from their FICON I/O investments. Switched-FICON is an industry best practice, and it is in your best interests to deploy it. Observations Remember that the last System Automation product version to support I/O Operations (SA z/OS z/OS 3.5) went out of service in September 2019. This means that the System Automation for z/OS (SA z/OS) used by administrators to manage the FICON I/O switch configuration, to make configuration changes, and to display status information has been removed. With the removal of SA z/OS I/O Operations, a new way to provide the management, configuration, and alerting functions is now required. The IBM Z team and Brocade have developed, over the years, new functions, built upon industry standards, to completely replace the I/O Operations component in switched-FICON implementations. Broadcom Mainframe-FICON-WP100 2 Mainframe White Paper Unlock the Full Value of Mainframe Technology with a Switched-FICON Architecture Emerging and evolving enterprise critical workloads and higher density virtualization are continuing to push the limits of SAN infrastructures. The Brocade Gen 6 family features industry-leading 32Gb/s performance and an impressive 12.2Tb/s chassis bandwidth to address these next-generation I/O and bandwidth-intensive application requirements. In addition, the Brocade Gen 6 provides unmatched slot-to-slot and port performance, with 1.54Tb/s of bandwidth per slot (port card/blade). And this performance comes in the most energy-efficient FICON director in the industry, using an average of less than 1 watt per Gb/s, which is 15 times more efficient than competitive offerings. The Brocade Gen 6 family enables high-speed replication and backup solutions over metro or WAN links with native Fibre Channel (10, 16, or 32Gb/s) and optional FCIP (1, 10, and 40GbE) extension support. This is done by integrating this technology via a FICON director blade (SX6) or by deploying a standalone switch (Brocade 7840). Finally, this is all accomplished with unsurpassed levels of reliability, availability, and serviceability (RAS), based upon more than three decades of Brocade experience in the mainframe space. This experience includes originally defining the FICON standards and authoring or co-authoring many of the FICON patents. Detailed Investigation IBM Z delivered High Performance FICON (zHPF) in 2008 on the z10 EC platform and has been strategically investing in this technology ever since the initial delivery. The raw bandwidth of a z15’s FICON Express16SA channel with zHPF is 5.2 times greater than a FICON Express16SA channel using “native” FICON capabilities. The raw I/O per second (IOPS) capacity of a z15’s FICON Express16SA that utilizes zHPF is 300,000 IOPS, which is 13 times greater than a FICON Express16SA channel that utilizes “native” command mode FICON capabilities. With these improved capabilities, organizations need to transition to zHPF to reap the full benefits of the z15. Within native command mode FICON, the number of open exchanges is limited by the FICON Express feature. FICON Express16SA, FICON Express16S+, FICON Express16S, FICON Express8S, and FICON Express8 allow up to 64 open exchanges. One open exchange (an exchange pair, actually) in command mode is the same as one I/O operation in progress. Within enhanced zHPF FICON transport mode, one exchange is sent from the channel to the control unit (CU). Then, the same exchange ID is sent back from the control unit to the channel to complete the I/O operation. The maximum number of simultaneous exchanges that a channel can have open with the CU is 750 exchanges on the z15 processor family. The CU sets the maximum number of exchanges in the status area of the transport mode response information unit (IU). The default number is 64, which can be increased or decreased. It is only when a director or switch is used between the host and the storage device that the true performance potential inherent in these channel bandwidth and I/O processing gains can be fully exploited. Switched-FICON Is a Best Practice In this section, we will explore the details behind each of our switched-FICON recommendations. Replacing the I/O Operations Component of System Automation for z/OS Prior to release 4.1, IBM System Automation for z/OS (SA z/OS) contained the I/O Operations (IOOPs) component to manage ESCON and FICON I/O switch configuration, make configuration changes, and display status information.