StorageTek Host Software Component 6 User Manual

1st ed., 6/30/04 - 312579601

The BACKup utility allows you to back up the library control data set. The control data set 
is the single most important resource required in the operation of the HSC. Various 
controls and services are available to keep the control data set intact and to enable you to 
recover the data set from a total failure. Features such as shadowing, journaling, backup, 
and restore, are all intended to provide for the integrity of the control data set. A library 
can have the following control data sets: 

• Primary control data set. Every installation must have this data set. It contains the 

inventory of all cartridges in the library, the library configuration, information about 
library hardware and resource ownership across multiple processors, and serves as a 
vehicle of communication between the HSCs running on multiple processors. 

• Secondary control data set. This optional data set is a duplicate copy of the primary 

control data set. 

• Standby control data set. This data set is optional. It is a formatted control data set 

with only one valid record, the Database Heartbeat (DHB). It is highly recommended 
that a standby control data set be created and initialized in your installation. This 
database is used primarily for control data set recovery. 

The BACKup utility can be executed with or without functioning library host software. 

Note: Backup to tape is not supported. 

The following items justify running the BACKup utility:

• regularly scheduled backups can be run to prevent inadvertent loss of information 

• the primary and/or secondary copy of the control data set for your library has been 

deleted or corrupted 

• in a multi-processor environment, due to a CDS switch on one processor, the primary 

and secondary CDS might run independently and become unsynchronized. 

In such a situation, you must determine which of two non-identical control data sets 
is the correct copy; the BACKup utility assists you in recovery.

• to choose the CDS with the most current updates if a database mismatch is detected. 

Refer to “When CDS Copies Are Split Among Hosts After an Error” on page 213 for the 
procedure to recover control data sets in remote-linked libraries.