Maintaining the Volume Master File › Correcting Chaining Errors › Breaking Valid Chains

Breaking Valid Chains

This process breaks volume chains that have been previously established. The chain must be broken at the base record of a scratch volume. When input tape data sets that were created outside CA TLMS are concatenated together, the volumes are chained in the VMF (unless a system modification specifies not to chain on input). To break a volume/data set chain, use the following command:

UPV vvvvvv,CHV=BRKCHN

Where:

vvvvvv

Represents the base volume serial number of the multivolume data set or multi-data set volume.

This command resets the volume sequence, volume count, file sequence and file count fields on the VMF. It also clears all data set related fields for all volumes in the chain.

The following steps are used to reestablish chains after they are broken:

1. Establish the base volume and update the data set-related fields (this reinitializes the VOLSEQ, VOLCNT, FILESEQ, and FILECNT fields).
2. Use the appropriate command to rebuild the volume/data set chain (see "Rebuilding Volume/Data Set Chains" on Rebuilding Volume/Data Set Chains).