StorageTek 6 manual Define High Dispatching Priority for the HSC

Define High Dispatching Priority for the HSC

The VM dispatch priority and SHARE settings of the ACS service machine may be altered to improve overall HSC performance for a VM host system.

Set High-Performance Host-to-Host Communications

In a multi-host ACS configuration, host-to-host communications allows hosts to notify each other of a CDS switch. Host-to-host communications can be accommodated through three performance levels of communications, ranked as follows:

•ACF/VTAM

•the LMU(s)

•the CDS.

The high-performance telecommunications method is through VTAM. This method is recommended by StorageTek. Host-to-host communications through the control data set should be used only as a backup facility. You should implement the highest level of host-to-host communications available.

‘‘Communication Functions’’ and ‘‘Communications Path (COMMPath) Command and Control Statement’’ in the HSC Operator’s Guide describe how multiple hosts are connected by any of the three possible communication methods. You have the capability to set or dynamically switch the host-to-host communication method between each pair of hosts. You can monitor the level of communication using the Display COMMPath command. If a level of communications fails, it automatically drops to the next lower level, allowing the HSC to continue without interruption.

The communications parameters can be modified dynamically, using the COMMPath command, without halting HSC execution.

Detailed Information about Host-to-Host Communications

Refer to “Communication Functions” on page 78 and to ‘‘Communications Path (COMMPath) Command and Control Statement’’ in the HSC Operator’s Guide for a general description of communication functions.

Refer to “PARMLIB Control Statements” on page 83 for how to define communication functions in a PARMLIB control statement.

The HSC Operator’s Guide contains information about the operator commands for controlling the host-to-host communication path.

Chapter 6. Performance Considerations 417

1st ed., 6/30/04 - 312579601