The VVDS is a VSAM entry-sequenced data set that has a 4KB control interval size. It contains information about the VSAM and SMS-managed non-VSAM data sets residing on the volume with the VVDS.

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

The VVDS is composed of a minimum of two records:

1. A VSAM volume control record (VVCR)
2. A VVDS self-describing volume record.

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

The second logical record in the VVDS is the VVDS self-describing VVR (VSAM volume record). This self-describing VVR contains information that describes the VVDS.

The remaining logical records in the VVDS are VVRs for VSAM objects or non-VSAM volume records (NVRs) for SMS-managed non-VSAM data sets. The hexadecimal RBA of the record is used as its key or identifier.

Figure 1 shows the general structure of a VVDS.

Figure 1. VSAM Volume Data Set (VVDS) Structure