Multiple data set groups

HD databases can be stored on multiple data sets; that is, the HD databases can be stored on more than the one or two data sets required for database storage.

The following database types support multiple data set groups:

• HDAM
• PHDAM
• HIDAM
• PHIDAM

When storing a database on multiple data sets, the terms primary and secondary data set group are used to distinguish between the one or more data sets that must be specified for the database (called the primary data set group) and the one or more data sets you are allowed to specify for the database (called secondary data set groups).

In HD databases, a single data set is used for storage rather than a pair of data sets. The primary data set group therefore consists of the ESDS (if VSAM is being used) or OSAM data set (if OSAM is being used) on which you must specify storage for your database. The secondary data set group is an additional ESDS or OSAM data set on which you are allowed to store your database.

As many as ten data set groups can be used in HD databases, that is, one primary data set group and a maximum of nine secondary data set groups.