StorageTek 6 manual CDS Recovery Capabilities, Dynamic Recovery of the Control Data Set

CDS Recovery Capabilities

Capabilities to recover the CDS from certain hardware and software failures are inherent in the HSC. CDS recovery capabilities include:

•dynamic recovery of the control data set

•control data set error diagnostics

•initializing/running on one copy of the control data set

•switching to another copy of the control data set

•control data set integrity during BACKup and RESTore

•detecting mismatch of control data sets

Additional recovery information is available in the HSC Operator’s Guide pertaining to the following topics:

•cartridge recovery

•errant cartridge recovery

•switch to standby LMU

•automatic downward switch of the host-to-host communication method level

•starting the HSC at the base service level

Control Data Set Recovery

Dynamic Recovery of the Control Data Set

At HSC installation, specifying additional control data sets, secondary and standby, in the LIBGEN SLIRCVRY macro indicates that these additional copies of the control data set are maintained by the HSC during library operation and kept on DASD. In addition, a CDs operator command provides you with the capability to enable or disable any of the various control data sets. An auto-enable function of the command sets the automatic switch capability of the HSC to automatically switch operation to another control data set.

If a failure occurs accessing the primary control data set, the HSC automatically switches operation to the secondary control data set. At the time that the switch to the secondary control data set occurs, the standby control data set becomes valid. After library operation continues with the secondary control data set, should the secondary control data set become inaccessible, the standby control data set is accessed and used by the HSC to keep the library operating.

Note: If the primary and secondary control data sets fail simultaneously, without sufficient time for the HSC to make the standby data set valid and accessible, HSC operation is impaired.

These backup data sets replace a failing control data set; however, they retain their original data set name.

Chapter 5. Problem Determination, Diagnostics, and Recovery 385

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