The combination of versatility of the connectivity options, the use of open standards, and the separation of data processing and I/O operations.
Data is produced on an unprecedented scale and access to that data must be quick, safe and guarantee integrity. Data is an organization's most valuable asset in the digital age. As the growth continues it is essential that the technology improves to keep the organization competitive.
The most efficient IT infrastructures that handle today's workloads usually have well balanced systems with superior data processing and I/O capabilities that are responsive and reliable. Such I/O capabilities have been a standard component of the IBM mainframe architecture since first introduced with the IBM S/360 in 1964. Over the past 50+ years I/O technologies have advanced significantly and so have the mainframe I/O capabilities. From the original parallel channels, where I/O devices were connected directly using two copper cables (called bus cable and tag cable) to today's Fibre Connection (FICON®), where optical transmitters, Fiber Channel switches/directors, and fiber-optic cables transport data at link rates of 2 Gbps, 4 Gbps, 8 Gbps, or 16 Gbps. A bus cable only carried one byte of information each way and a tag cable indicated the meaning of the data on the bus cable.
In addition, z Systems platforms have a unique channel subsystem that delivers high I/O bandwidth. The channel subsystem (CSS) was added to the IBM mainframe architecture to provide a pipeline through which data can be exchanged between systems or between a system and external devices via storage area networks and local area networks. The CSS is the channel path management layer that enables communication to and from system memory and peripheral devices at very fast rates.
The z Systems platforms have dedicated system assist processors (SAPs) in addition to the general purpose and specialty processors. I/O requests are handled by the SAPs, freeing up the general purpose and specialty processors to do other work. The IBM z13 offers up to 24 SAPs, supporting millions of I/O operations per second. This is also possible because all I/O features offered on the z Systems platforms offload some of the I/O operations to the hardware, using licensed internal code (LIC). The result is a significant improvement in both latency and bandwidth for transporting data.
In the z13, I/O features are plugged into an industry standard PCIe I/O drawer with PCIe Gen3 interconnects, delivering throughput speeds of 16 GBps to and from the I/O features. Different types of I/O features are available for each channel or link type and they can be installed or replaced concurrently, so no disruption to the production environment. Each PCIe I/O drawer can support up to 320 FICON channels, which provide unmatched bandwidth to back-end storage systems, while up to 96 OSA-Express ports allow for direct high-speed Ethernet connectivity.
Other I/O features used for system-to-system communications are Integrated Coupling Adapter (ICA SR) and 10GbE RoCE Express (for IBM z/OS®-to-z/OS communications), while HiperSockets technology can be used for communications between logical partitions within the z Systems platform.
If you would like to learn more about z Systems connectivity options, typical uses, coexistence, and relative merits of the available I/O features, go to:
- IBM z13 Technical Guide, SG24-8251
- IBM z Systems Connectivity Handbook, SG24-5444
Get More Out of Your IT Infrastructure with IBM z13 I/O Enhancements, REDP-5134