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System z Innovations Automatically Define Configurations for Greater Availability

Mainframe I/O Configuration Definition

Collectively, these foundational autonomic technologies optimize I/O execution in host and storage subsystems to meet specified goals within the bounds of existing I/O configurations. With them in place, organizations can enhance the configuration definition process to allow incremental updates to running systems to be more automated. The new zEnterprise* zDAC functions provide this capability.

Mainframes provide the infrastructure zDAC needs. Host software can interrogate the SAN fabric name server and SAN fabric N_Ports to discover I/O configuration changes. When the OS analyzes potential updates, it can determine the I/O configuration changes needed to allow use of the devices and control units. Meanwhile, it maximizes I/O availability characteristics and performance capabilities within policy limits specified by the client in HCD. zDAC allows z/OS and System z technology to discover the information about new I/O resources needed to make smart I/O configuration proposals. These proposals take all single points of failure in the physical host, SAN and target storage subsystems into account.

FICON technology and the DS8000 enterprise class storage subsystem on System z provide reliable access to data and virtually guarantee the data is correct.

zDAC simplifies I/O configuration, eliminating errors that occur when physical configurations don’t match information used to create host I/O definitions. When they don’t match, several symptoms will be surfaced to the z/OS staff. These include z/OS health checks that periodically explore I/O configurations for availability risks. Other errors arise when I/O device paths are found to be nonoperational, or from mis-cabling issues.

Although z/OS technology helps ensure configuration errors won’t cause data corruption, it cannot prevent suboptimal availability characteristics when a configuration is incorrectly defined. When this happens, clients can optionally run z/OS health checks that will identify the single points of failure when they occur. They must carefully look for these symptoms of configuration errors and fix them before a failing component jeopardizes the system.

HCD and zDAC provide an additional tool that helps validate the physical security of the host and storage subsystems in the SAN. HCD presents a list of available FICON storage subsystems and hosts visible from each system. This allows clients to verify that devices and hosts have been isolated from each other using soft- and hard-zoning SAN functions.

Continued Leadership

With the highest degrees of resource utilization, z/OS technology offers the capability to meet client goals while running diverse workloads. The I/O capabilities are designed to provide predictable, repeatable I/O performance when running these workloads, including running online transaction processing concurrently with batch and backups. FICON technology and the DS8000 enterprise class storage subsystem on System z provide reliable access to data and virtually guarantee the data is correct. In addition, System z features built-in, in-band I/O instrumentation. The mainframe uniquely measures components of I/O service times, with industry leadership in I/O delay measurement, effective I/O management algorithms and data integrity.

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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