increase the generation without loosing existing generation.

[Jagjeet Dayal]

Hi everyone,

i have a question, if I have GDG generations with limit 10 , now i want increase the generation limit to 30 how i can achieve it ? i mean without recreating the GDG again with 30 generations limit, in that case i'll be loosing the existing 10 generations, so without disturbing the existing generations i want to increase the limit to 30 how this can be achieved ?

[Robert Sample]

Try this:

Code: Select all

//STEP1 EXEC PGM=IDCAMS
//SYSIN DD *
ALTER YOUR.GDG.NAME LIMIT(30)
/*

One note: if you change the limit and decrease it, then generations will be rolled off so the GDG matches the new limit.

[Antonsig]

Have you successfully implemented the suggested IDCAMS code to increase the generation limit without losing the existing generations in your GDG?

[Jagjeet Dayal]

Try this:

Code: Select all

//STEP1 EXEC PGM=IDCAMS
//SYSIN DD *
ALTER YOUR.GDG.NAME LIMIT(30)
/*

One note: if you change the limit and decrease it, then generations will be rolled off so the GDG matches the new limit.

Thanks Robert. Understood. When you say roller off that means "they are deleted? ". If yes, what happens to the data in them?

[Robert Sample]

"When you say roller off that means "they are deleted? ". If yes, what happens to the data in them?"  Depending upon how your site is set up, they may be immediately deleted or they may be in ROLLED-OFF status for some period of time.  Eventually, they will be deleted.  And just like any other sequential data set that is deleted, the data in them will be lost, never to be seen again.

[Dimnaslore]

Have you successfully implemented the suggested IDCAMS code to increase the generation limit without losing the existing generations in your GDG, and do you have any concerns about the potential loss of data in case of decreasing the limit?

[Jagjeet Dayal]

"When you say roller off that means "they are deleted? ". If yes, what happens to the data in them?"  Depending upon how your site is set up, they may be immediately deleted or they may be in ROLLED-OFF status for some period of time.  Eventually, they will be deleted.  And just like any other sequential data set that is deleted, the data in them will be lost, never to be seen again.

 

Thanks Robert.

Sorry to bother you again, but what does

Depending upon how your site is set up

 

What thing plays a role to decide this?

[Jagjeet Dayal]

Have you successfully implemented the suggested IDCAMS code to increase the generation limit without losing the existing generations in your GDG, and do you have any concerns about the potential loss of data in case of decreasing the limit?

Yes, IDCAMS solution is working fine for me.

[Robert Sample]

I try not to give absolute answers because there are so many different ways to configure a mainframe.  A GDG, for example, may be SMS-managed or non-SMS-managed and how they behave is slightly different.

[Jagjeet Dayal]

Thanks Robert. Now I am not sure what is SMS in your reply.

[zum13]

In days of old, when you allocated a dataset you needed to tell the system where to put it (i.e. which volume to use). This created problems, particularly where production jobs were concerned. You could, essentially allocate anywhere, but if that anywhere was full your job would fail. It also lead to a load of conversations with systems programmers telling you to keep your data off of certain volumes, or to allocate smaller datasets.

System Managed Storage is a solution to these problems which allows an installation to create a set of rules for the allocation and mangement of datasets which includes removing the requirement to explicitly specify volumes. SMS can, based on criteria set by your administrators, determine which volumes it is appropriate for you or your job to use, how they are managed (e.g. are they to be migrated and backed up by HSM), place restrictions on the size of datasets, even decide the LRECL and RECFM of the dataset based on the dataset name. User data can be assigned to one set of volumes, data for production datasets can be assigned to another and the whole thing is automatically managed.

An SMS managed dataset is one which falls within the management rules defined by your local administration. A non-SMS managed dataset is one which falls outside of those rules.