July 17, 2017 marked the IBM announcement of the latest IBM mainframe: the IBM z14. Congratulations to the IBM Z team on a successful launch of what looks to be yet another in a long and distinguished history of superb enterprise computing platforms. Similar to the z13 launch in 2015, the z14 features several new, impressive I/O features and functionality that will provide tremendous business and technical value to IBM Z clients. In the remainder of this post, I’ll discuss the highlights of what I view to be the two most important features: FICON Express 16S+ channels, and zHyperLink Express. I will also discuss the synergy between these new technologies with Brocade's latest Gen 6 FICON SAN technology. Watch for follow-on blog posts that will cover how Brocade enables these two technology topics in more detail separately.
The FICON Express16S+ channel shares many of the same characteristics as the prior generation FICON Express16S channel. However, there are some enhancements made that have resulted in truly impressive performance gains. In IBM performance testing, using z14 with FICON Express16S+, the z High Performance FICON (zHPF) protocol and small data transfer I/O operations, IBM reported results of just over 300,000 IOs/second. That is over three times the IOPS capability of the FICON Express16S channel with z13!
In testing a workload using zHPF and a mix of large sequential read and write data transfer I/O operations, IBM reported a maximum full duplex throughput of 3200 MB/sec (reads + writes) on z14 compared to 2560 MB/sec for the same test on z13 and FICON Express16S channels. This 25% increase demonstrates that the z14 with the new FICON Express16S+ channels maximizes the channel bandwidth, running full line rate, full duplex. Additionally, as you can see in the graphic, the performance testing results using the FCP protocol typically used in Linux on Z environments were even more impressive for IOPS capability when compared to z13 and FICON Express16S.
What does this mean? If you currently use SSD/flash storage in your mainframe environment (hybrid or all flash arrays), or are planning on doing so during this mainframe product cycle, you will see significantly enhanced data center application operations and performance improvements with greater IOPS and lower latency with the FICON Express16S+ channels.
To take advantage of the capabilities of the FICON Express16S+ channels, just remember to upgrade the FICON storage network that connects it all together. If you are still using the original DCX/DCX4-S FICON directors for your FICON SAN and planning on implementing z14, please be aware that Brocade and IBM are not qualifying those legacy FICON directors with the z14. While the DCX and DCX4-s are still not end of support, keep in mind that those FICON directors were released in Feb 2008, the same date as the IBM z10. They were built for the Z technology of that era, not today’s Z.
Yours truly was on the SHARE Board of Directors at the time and was there for the unveiling of the z10 on the SHARE technology exchange floor. Look at the test results graphic to compare the z10 to the z14 with the FICON Express16S+ channels. Keep in mind that the z10 was announced with FICON Express 4 channels which are not even in the test results. Since the release of the z10, IBM has evolved through four generations of mainframe (z196, zEC12, z13, z14). The bottom line, the DCX and DCX4-S directors, as capable as they were, simply were not designed to handle the capacities of the z14 and FICON Express16S+ channels.
If you are contemplating a z14 purchase, at a minimum, your solution needs the Gen 5 (16Gbps) DCX8510 family of FICON directors. If you have implemented, or are planning to implement, flash/SSD storage with the new z14, then ideally upgrade your solution to the latest, Gen 6 FICON SAN technology with the Brocade X6 family of FICON directors. The X6 directors with Gen 6 technology are capable of transmitting approximately 35% more frames per second than the DCX8510 directors. This translates into more IOPS and lower latency. Gen 6 technology also offers up to 32 Gbps bandwidth per port for next generation channel cards. Higher IOPS and greater bandwidth make Gen 6 FICON SAN technology ideal for the z14 and FICON Express 16S+ channels.
This is the most revolutionary mainframe I/O technology to appear since FICON made its debut nearly 20 years ago. IBM zHyperLink Express is a direct connect short distance (150m), IBM Z I/O adapter offering extremely low latency connectivity to IBM FICON attached DS8880 storage arrays. Working in conjunction with your existing FICON SAN infrastructure, zHyperLinks fosters a new I/O paradigm for IBM mainframes. zHyperLinks is a new technology that works with your FICON SAN infrastructure to provide up to a five times reduction in I/O latency times for DB2 v11 and v12 read requests with the qualities of service IBM Z clients expect from I/O infrastructure. zHyperLinks reduce latency via synchronous I/O techniques and by interconnecting the z14 CPC directly to I/O Bay of the DS8880, using PCIe Gen3 x 8 physical link (up to 150m distance).
Part of the zHyperlink technology contributing to the impressive latency reduction is using synchronous I/O as the I/O model type. Synchronous I/O is sometime referred to as polling driven I/O, in contrast to asynchronous I/O which is interrupt driven. Synch I/O allows the operating system to read data records synchronously, and avoid the scheduling and interrupt overhead associated with Async I/O operations. Where these types of improvements really come into play are when using Sync I/O techniques to attached to SSD/flash storage. Scientists from Intel have demonstrated nearly 40% reductions in latency using Sync I/O techniques with 4K block size traffic with Linux applications.
There are caveats described by IBM regarding the performance testing for zHyperLink Express and I encourage you to read the details of this new technology. Harry Yudenfriend had a great presentation on zHyperLinks at the August 2017 SHARE Providence conference and I have included that as a file attachment to this post.
Two very important points to emphasize: zHyperLink Express connections complement FICON connectivity, they do not replace FICON. Also, they only support z/OS and ECKD.
To learn more about how Brocade Gen 6 technology can unlock the true performance of the latest mainframe technology and deliver better insight for your mainframe environment, check out the “Better Performance, Better Insight for Your Mainframe Storage Network with Brocade Gen 6” whitepaper, which can be downloaded at the link provided. It also is attached to this post.
Thanks for reading. Thoughts/comments/questions are always welcome. You can reach me at email@example.com, and follow me on Twitter: @DrSteveGuendert.