StorageTek 6 manual Control Data Set Recovery Techniques, User Control of Control Data Sets

Control data sets can be accessed by different hosts and are kept synchronized. In event of a failure, the BACKup and RESTore utilities can be used to perform extensive error checking and synchronization of the data. A backup control data set and journals are used to reconstruct the control data sets.

The integrity of the control data sets is extremely important. In multiple processor environments, data set integrity is much more difficult to maintain. Because of this, the HSC subsystem is designed to keep the control data sets intact and configured to recover from failures. Features such as shadowing for the control data set, journaling, backup and restore were previously in place in prior releases to maintain data set integrity.

Control Data Set Recovery Techniques

There are several techniques to accomplish control data set recovery. These techniques are:

•dynamic recovery of CDS errors (when possible)

-switch

-internal CDS directory rebuild

-standby CDS copy.

•diagnostic information on CDS errors, error detection, and correction of the CDS through the BACKup and RESTore utilities

•the ability of the HSC to continue running on one copy of the CDS

•user control of enabling and disabling control data sets with operator commands

•automatic communication with other hosts in a complex when control is switched from one CDS to another.

User Control of Control Data Sets

The HSC offers flexibility for definition and control of control data sets. User control of these data sets includes:

•allocation of data sets at initialization

•ability to dynamically enable or disable the library control data sets

•reassigning control data set names in the Database Heartbeat record.

Allocation of Control Data Sets

Control data sets are defined at HSC initialization by PARMLIB control statements rather than defined by JCL. These definitions are invoked at HSC initialization and remain set until HSC termination. The definitions cannot be altered without HSC shutdown and restart.

Refer to “PARMLIB Control Statements” on page 67 for detailed information about PARMLIB control statements.

Chapter 2. Host Software Component Functions 59

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