GDG generation define and reference..

Anuj Dhawan · Posted: Sun Sep 21, 2008 7:07 am

Hi,

Dick & Expat has given the best suggestion, well, for my .02 cents ..read on..

The files within a GDG are assigned names derived from the name of the base and have a generation number added to the end so as to give each file an unique name. For example if the GDG base is called PROD.XXXXXX.INPUT then the first file created within this GDG will be given the name PROD.XXXXXX.INPUT.G0001V00 and subsequent files will be named by incrementing the generation number giving filenames ending in G0002V00, G0003V00, etc. all the way to G9999V00 after which the numbering will start again from G0001V00. The two zeroes on the end of the name used to represent a volume number which is used when the file is stored on media requiring the use of multiple volumes. Since multi-volume storage is now rarely required the last two digits are now usually used for version control instead.

You can use the number on the end of the filename to create a replacement dataset within a GDG without overwriting the original file. For example if PROD.XXXXXX.INPUT.G0013V00 exists and you create PROD.XXXXXX.INPUT.G0013V01 then both files will exist with only the last one created being attached to the GDG. This is effectively the same as creating two ordinary datasets except that one of them also belongs to a GDG. Of course if you then delete and recreate PROD.XXXXXX.INPUT.G0013V00 then this will be the one belonging to the GDG (since it was the last one created) so you can't rely on the volume number to tell you which one belongs to the GDG. With a properly created multi-volume GDG (that is one created using a relative record number rather than a full name) all of the volumes belong to the GDG and the full name including the volume number is only used internally to GDG processing when creating the volumes in the first place and you only see it when you are reading the dataset back in and the system needs to ask for you to mount the next volume

helga · New User Joined: 11 Sep 2006 Posts: 23

I'd dispute this.

Either using relative generation numbers or explicit GooVoo numbers, you can only have one version of a generation a GDG - in the catalog at least.

That is to say that if you have A.B.C.G0003V00 and you explicitely create A.B.C.G0003V01, then the V00 is removed.

As for the reason for version numbers, I think it's quite simple, you might have a GDG that runs in a monthly job, so G0001 is Jan, G0002 is Feb etc, well if your Feb run abends and you rerun with (+1) then G0003 now applies to Feb. In this case, you might make G0002V01 to maintain consistency.

Likewise, knowing that (-3) is the file from three months ago might be important, but is not something you can rely on if when you restart jobs, you use (+1). Restarting with icremented version umbers and not generation numbers would avoind this problem.

What I'd like to know, and I'm sure I've done it before, is ... How can I specifically create a new version of the current generation?

dick scherrer · Posted: Tue Oct 07, 2008 2:06 am

Hello,

helga · New User Joined: 11 Sep 2006 Posts: 23

yes, it was poorly worded, but there's no Edit button ???

I meant, create a version using relative numbers like A.B.C(+0+1)

I thought I had done something like this before, but maybe I just used GnnnnV01

I did just cycle one through 9999 and it does go to 0001, which makes me wonder why they don't start Gen numbers at 00 like they do with Ver numbers, not that it really matters, it's just a little inconsistent.

dick scherrer · Posted: Tue Oct 07, 2008 2:21 am

Anuj Dhawan · Posted: Tue Oct 07, 2008 1:45 pm

So ..are the queris resolved..ot the dispute is still going on ..

..?

dick scherrer · Posted: Tue Oct 07, 2008 7:18 pm

Hi Anuj,

I believe we're done. . .

d

Anuj Dhawan · Posted: Wed Oct 08, 2008 12:29 pm

That sounds nice..

-Ad