VSAM Volume Record (VVR)

VSAM volume records contain information about the VSAM data sets residing on the volume with the VVDS. If more than one VVR is associated with a component, the first (primary) VVR contains information pertaining to the data set as a whole. The other (secondary) VVRs do not repeat the primary information in their records but contain information for their own component, such as extents, RBAs, and allocation quantities, and most of the information needed to open a VSAM data set.

The number of VVRs for VSAM data sets varies according to the type of data set and the options specified for the data set. Table 1 contains the number of primary VVRs for each type of data set.

Table 1. Number of Primary VVRs for Data Set Types
Data Set Type	Number of Primary VVRs
Entry-sequenced data set	1 per volume for the data component
Key-sequenced data set with the NOIMBED option	1 per volume for the data component; 1 for the index
Key-sequenced data set with the IMBED option	1 per volume for the data component; 1 for the index; 1 per volume for the sequence set
Key range key-sequenced data set with the NOIMBED option	1 per key range per volume; 1 for the index
Key range key-sequenced data set with the IMBED option	2 per key range per volume; 1 per volume for the index

The size of a VVR depends on its type (primary or secondary), and is determined by the combined lengths of VVR cells. Figure 1 shows the primary and secondary VVRs and the cells that constitute each VVR. These VVR cells are:

VVR header cell
VVR data set information cell
VVR AMDSB cell
VVR volume information cell

The VVRLEN field of the VVR header cell contains the length of the entire VVR. The VVRTYPE field of the same cell contains the VVR type code, which is either "Z" (for primary) or "Q" (for secondary).

Figure 1. VSAM Volume Record (VVR) Structure

Figure 2 shows examples of the information contained in each type of VVR cell.

Figure 2. Examples of VVR Cell Information