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DS8870 Innovations In Support of the z13 Platform


IBM z Systems* and storage technologies strive to deliver on certain core principles. Among them are adding value for client workloads with improved reliability, availability, performance and reduction in total cost of ownership. IBM also strives to match increased capabilities and capacity with increased I/O capabilities, I/O rates, bandwidth and latency. These are essential for existing workloads such as transaction processing and client demands for cloud, analytics, mobile, social and security.

Ever-increasing mobile- and analytics-initiated I/O activity stresses older IT systems’ capabilities, bombarding them with requests even as they provide new data to existing applications. Also, accelerating database transactions is good for business; consistently fast transactions yield higher user productivity and satisfaction. The IBM z13* system and DS8870 storage subsystem have been designed to meet these ever-increasing demands.

More Speed and Capacity

New FICON* Express16S channels available with the z13 platform provide additional I/O capacity to help balance the new processing power with I/O capability. In IBM testing, the modestly increased start rate of about 6.5 percent makes the maximum I/O start rate about 98,000 per second. Channel bandwidth is substantially improved to 2,600 MB/second, bidirectional. This represents a 63 percent improvement in a single channel’s I/O bandwidth. Perhaps the most important capability provided by the 16 Gb Fibre Channel (GFC) technology is a substantial reduction in I/O latency. When the FICON Express16S channel is used in combination with the DS8870 storage and 16GFC Host Adapter (HA) for a true end-to-end link speed of 1,600 MB/second, substantial improvements in I/O latency are achieved.

DB2* commit elapsed times with DS8870 zHyperWrite* technology combined with FICON Express16S on the z13 processor and 16GFC HA in the DS8870 were substantially improved by up to 61 percent as compared to FICON Express8S on an IBM zEnterprise* EC12 without zHyperWrite.

Large Systems Performance Reference IMS workload with FICON Express16S technology was demonstrated for the write ahead data set (WADS) and online log data set (OLDS). The IMS WADS data set, a critical path for IMS latency requirements, is improved by 14 percent as it does not yet exploit z Systems High Performance FICON (zHPF) protocols. The IMS OLDS data set, however, is eligible for zHPF and sees a more substantial 22 percent improvement in I/O service time.

The multistream read performance improved 39 percent and the multistream write performance improved 34 percent. Single stream read and write performance improved about 20 percent for each.

DB2 database updates are first written to the log and committed when log writes complete. zHyperWrite with FICON Express16S has a substantial improvement to DB2 commit latency up to 61 percent. FICON Express16S technology alone can provide up to 23 percent improvement in the DB2 log write I/O service time, also a substantial improvement.

During batch windows, client workloads typically make simultaneous large read/write I/O requests. For I/O bound jobs—meaning those that wait on I/O requests to proceed—FICON Express16S can reduce the elapsed time by as much as 25 percent.

The combination of the z13 FICON Express16S technology and the DS8870 16GFC HA provide substantial I/O latency reductions for zHPF I/O traffic.

Christopher Colonna is the FICON channel firmware execution team lead for z Systems, IBM Systems.

Roger G. Hathorn is a Senior Technical Staff Member for enterprise storage I/O architecture and development, IBM Systems.

Harry M. Yudenfriend is an IBM Fellow with Systems and Technology Group, System z and Power who joined IBM in 1980. He was named an IBM Master Inventor in 2001 and has achieved his 33rd invention plateau.



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