GDG

A GDG (Generation Data Group) is a collection of datasets that are logically related and share a common naming structure. It's commonly used to manage multiple versions of data over time

GDGs help in organizing datasets that are created on a regular basis like daily reports, backups, or job outputs making version control simple and automated

All datasets in a GDG share a common prefix, known as the GDG base.

Example: MYDATA.TEST.SAMPLE.GDG is the base name

Each dataset in the group is named using the base followed by a generation and version number. Example:

MYDATA.TEST.SAMPLE.GDG.G0001V00
MYDATA.TEST.SAMPLE.GDG.G0002V00

A GDG can have up to 255 generations at one time. When the limit is reached, older generations can be automatically deleted, based on how the GDG is defined (e.g., with a limit and a scratch or no-scratch option).

GDG datasets are usually sequential (PS), but they can also be partitioned (PDS)

All generations under a GDG must have the same dataset attributes, such as record format, record length, and dataset organization.

RULES

All generations within a GDG must share the same attributes. This includes DCB parameters like record format and record length, ensuring consistency across the group
A GDG can have up to 255 generations at a time. If you reach this limit, older generations may be automatically deleted, depending on how the GDG is set up.
Both DSN (the name of the dataset) and UNIT (where it should be stored) are required when allocating a new generation
When you're creating a new generation, make sure to set the DISP parameter to (NEW, CATLG, ...) in your JCL. This tells the system to treat it as a brand-new dataset and add it to the catalog.
GDGs don’t support VSAM datasets

USES

GDGs make it easy to manage files that are created on a schedule daily, weekly, monthly, or even yearly. Each version is stored neatly under the same base name, making everything easier to track.
GDGs automatically handle file versions for you. This reduces manual effort and prevents mistakes in using the wrong dataset
You can set a limit on how many generations to keep. When that limit is reached, older versions are automatically removed. This helps manage disk space without manual cleanup

PreviousIEBCOPY renaming member while copying NextGDG parameters

Last updated 26 days ago

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GDG

A GDG (Generation Data Group) is a collection of datasets that are logically related and share a common naming structure. It's commonly used to manage multiple versions of data over time

GDGs help in organizing datasets that are created on a regular basis like daily reports, backups, or job outputs making version control simple and automated

All datasets in a GDG share a common prefix, known as the GDG base.

Example: MYDATA.TEST.SAMPLE.GDG is the base name

Each dataset in the group is named using the base followed by a generation and version number. Example:

MYDATA.TEST.SAMPLE.GDG.G0001V00
MYDATA.TEST.SAMPLE.GDG.G0002V00

GDG datasets are usually sequential (PS), but they can also be partitioned (PDS)

All generations under a GDG must have the same dataset attributes, such as record format, record length, and dataset organization.

RULES

All generations within a GDG must share the same attributes. This includes DCB parameters like record format and record length, ensuring consistency across the group
A GDG can have up to 255 generations at a time. If you reach this limit, older generations may be automatically deleted, depending on how the GDG is set up.
Both DSN (the name of the dataset) and UNIT (where it should be stored) are required when allocating a new generation
When you're creating a new generation, make sure to set the DISP parameter to (NEW, CATLG, ...) in your JCL. This tells the system to treat it as a brand-new dataset and add it to the catalog.
GDGs don’t support VSAM datasets

USES

GDGs make it easy to manage files that are created on a schedule daily, weekly, monthly, or even yearly. Each version is stored neatly under the same base name, making everything easier to track.
GDGs automatically handle file versions for you. This reduces manual effort and prevents mistakes in using the wrong dataset
You can set a limit on how many generations to keep. When that limit is reached, older versions are automatically removed. This helps manage disk space without manual cleanup

PreviousIEBCOPY renaming member while copying NextGDG parameters

Last updated 26 days ago

Was this helpful?