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Flash Express Integrates Secure, High-Performance Storage Within System z

Illustration by Harry Campbell

For the first time, flash storage has been integrated into IBM System z* servers. This new function brings an enhanced client experience on enterprise applications by providing additional auxiliary storage with higher performance than external disks.

By extending auxiliary storage with Flash Express, IBM improves execution times for workload transition and reduces system dump times.

Called Flash Express, this feature is implemented with PCI Express (PCIe) adapters containing SSDs configured in RAID 10 arrays across cable-connected pairs in I/O expansion drawers. The initial exploitation of Flash Express is as an extension to main memory in z/OS* where it’s integrated within the memory hierarchy and administered by the z/OS memory manager to provide increased system availability and resiliency during paging-intensive events.

Benefits of Flash Express

Server installations are being pressured to deliver increasingly higher levels of availability in nearly every industry—especially finance, banking and healthcare. With Flash Express, the system can reduce workload and response-time delays caused by increased memory pressure during periods of peak demand, transitions between workloads or diagnostic collection.

For example, when transitioning from a transactional workload during a prime shift to a batch workload, and then back again during the next prime shift, response-time delays can occur. The system can reduce these delays by using Flash Express when data for the prime shift must be transferred from auxiliary storage into main memory. Flash can also help when the system must transfer data into main memory as part of a diagnostic dump. The increased I/O bandwidth achieved with Flash Express provides better first-failure data capture time and faster page-ins of critical work, thus allowing the system to return to normal workload operations significantly faster.

Flash memory has been integrated into the z/OS memory hierarchy to provide higher levels of availability and speed. As databases and Java* VMs consume larger amounts of memory to provide better transactional response times, lowering the memory management cost can only help improve overall response times. Typical fast random access and higher I/Os per second for reads in flash memory—relative to disk drives—have enabled the z/OS platform to provide the support for pageable large (1 MB) pages. Managing memory in 1 MB granularity vs. traditional 4 KB benefits application performance by reducing memory management costs. By exploiting large pages, today’s data-intensive applications with large memory footprints can transfer larger chunks of data at faster speeds between main memory and Flash Express. This can translate into better throughput and performance for DB2*, Java and other analytic workloads.

Implementation Overview

The Flash Express subsystem encompasses three major components:

  1. System support element (SE)
  2. Main compute complex (CEC)
  3. Flash adapters

Much of the flash management is accomplished using new SE panels. Through the Flash Increment Allocation panel, flash memory increments can be assigned to partitions.

On the CEC, the flash software stack is split between z/OS running in a partition on general-purpose processors and the I/O firmware running on system assist processors. The flash memory resides on PCIe adapters plugged into I/O drawers. These adapters are installed in pairs connected to each other with dual redundant external mirroring cables for resiliency.

Edward W. Chencinski a senior technical staff member and chief engineer of an I/O subsystem development team within IBM Systems and Technology Group.

Peter Szwed is a senior engineer and IBM Master Inventor in the Systems and Technology Group.

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