What is a VSAM Volume Data Set (VVDS)?

VVDS stands for VSAM Volume Data Set and it’s a VSAM file that contains the information of all VSAM and SMS-managed non-VSAM data sets that reside on the volume where the VVDS file is allocated.

A VVDS is recognised by the restricted data set name SYS1.VVDS.Vvolser, where volser is the volume serial number of the volume on which the VVDS resides.

 

VVDS Structure

Record

Description

VVCR

The VSAM Volume Control Record (VVCR) is the first logical record in a VVDS. The VVCR contains information for management of DASD space and the Base Catalog Structure (BCS) names, which currently have VSAM or SMS-managed non-VSAM data sets on the volume. The VVCR might have a pointer to an overflow VVCR.

Self-Describing VVR

The VVDS self-describing VVR (VSAM Volume Record) is the second logical record in the VVDS. The self-describing VVR has the information that describes the VVDS.

VVR or NVR

The remaining logical records in the VVDS can either be VVRs (VSAM Volume Records) for VSAM objects or NVRs (Non-VSAM Volume Records) for SMS-managed non-VSAM data sets. The hexadecimal RBA (Relative Byte Address) of the record is used as its key or identifier.

VVR or NVR

VVR or NVR

 

As a minimum, the VVDS contains two records:

  1. A VSAM Volume Control Record (VVCR)
  2. A VVDS self-describing volume record

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