StorageTek Host Software Component 6.0, Руководство системного программиста

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Chapter 6. Performance Considerations 419
1st ed., 6/30/04 - 312579601
Define Secondary and Standby Control Data Sets
Various controls and services are in place in the HSC subsystem to ensure that the primary
control data set maintains its integrity. Included among the controls are the capability to:
• designate secondary and standby control data sets as backup
• run BACKup and RESTore utilities
• designate journal data sets for use in recovery of control data set errors.
However, though all of these means are available, you must configure your installation to
take advantage of the capabilities. At installation, when defining the library configuration,
it is important that you initialize the additional control data sets.
It is highly recommended that secondary and standby data sets be used to ensure the
performance and reliability of your library.
Refer to Chapter 7, ‘‘Allocating and Initializing Control Data Sets’’ in the HSC
Installation Guide for information about defining control data set requirements at HSC
installation.
The HSC Operator’s Guide contains information about the operator commands to control
switching of control data sets.
Limit View Time to Maintain High Performance
Certain conditions within a library can significantly affect performance. These conditions
may occur because of software issues or simply because of daily procedures used within a
data center. The VIew command is invoked to improve performance because it can be
used to quickly resolve problems. It can often eliminate the need for an operator to open
an LSM door and enter the LSM to resolve a problem. Excessive use of the VIew
command is a typical example of how library performance can be drastically affected
unless you plan and consider how it can impact the performance of your library.
Note: The SL8500 library does not contain a camera, so the VIew command is not
useful in that environment.
Though the VIew command is primarily used by operators, it is important for systems
programmers to know that excessive use of the VIew command for extended periods of
time can impact the performance of an LSM and your library. However, you should use
the VIew command to inspect the interior of an LSM rather than place the LSM in manual
mode and physically enter the LSM. If it is necessary to inspect the robot, its hands, and/or
cameras, you must modify the LSM offline and enter through the access door.
Default view time can be controlled with the OPTion command’s Viewtime parameter.
The system default for view time is 10 seconds. However, you can change this default
value to fit your needs.
Refer to ‘‘Option Command and Control Statement’’ in Appendix A, ‘‘Macros, Control
Statements, Utilities, and Commands Syntax Reference’’ or to Chapter 2 in the
HSC
Operator’s Guide for detailed information about the OPTion command’s syntax and
parameters.