Control and Cache Data Sets › Control Data Sets

Control Data Sets

The control data sets consist of the following:

Local VCAT

This file records information specific to a single CA Vtape Subsystem. Each Subsystem must have its own unique Local VCAT. The Local VCAT is used primarily as a work area for transient information and to contain the attribute settings loaded from parmlib. Since it is a work file, it is not backed up and restored for disaster recovery. Instead, a new one is defined.

Global VCAT

This file records multi-system control information such as Virtual Volume status. This file is shared by all of the Subsystems participating in a CA Vtape Complex. Since it is mirrored by the BSDS1, the Global VCAT is not backed up and restored for disaster recovery. Instead, it is recovered from the BSDS1.

BSDS1

This file records information necessary to recover the Global VCAT. Like the Global VCAT, this file is shared by all of the Subsystems participating in a CA Vtape Complex. The BSDS1 is backed up for disaster recovery.

The control data sets should be considered critical system files. Keeping these files on high performance, reliable media, such as a RAID-compliant DASD, will help to improve overall performance and minimize potential system outages. Maintaining current backups of the BSDS1 and keeping the Global VCAT and BSDS1 on separate DASD volumes is critical to insuring recoverability if the hardware unexpectedly fails.

A Hardware Reserve is used processing to serialize access to the Global VCAT. The Hardware Reserve may require you to isolate this data set on a single DASD volume.