Hi Rex,
VVDSs came with ICF. Before that, VSAM Clusters were ALLOCATED as either
SUBALLOCATION or UNIQUE.
SUBALLOCATION meant that the user ALLOCATED a "cloud" (i.e. DEFINE
SPACE) to hold 1 or more VSAM suballocated Dataset.
It was conceptually similar to a PDS and Members.
Regards,
David
On 2024-05-24 11:10, Pommier, Rex wrote:
David,
Since you are obviously my elder in the field, please enlighten me as to what
the VVDS was before the ICF catalog came along. When I started, VSAM catalogs
were still a thing (as were CVOLs I think) but we never had them at my shop. I
was taught that the VVDS and BCS structures were the 2 components of an ICF
catalog, created to overcome shortcomings of the VSAM catalog. Did VVDS's
exist before the ICF catalog or were they introduced with ICF?
Rex
-----Original Message-----
From: IBM Mainframe Discussion List <IBM-MAIN@LISTSERV.UA.EDU> On Behalf Of
David Spiegel
Sent: Friday, May 24, 2024 9:33 AM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: [EXTERNAL] Re: VTOCs vs. catalogs
Hi Rex,
You said: "...I never worked with either CVOLs or VSAM catalogs ..." If I may take the
Bible out of context, please see: DE 32:7 זְקֵנֶ֖יךָ וְיֹ֥אמְרוּ לָֽךְ "... Remember the days
of old, Consider the years of ages past; Ask your parent, who will inform you, Your elders, who
will tell you: ..."
Regards,. David
On 2024-05-24 10:12, Pommier, Rex wrote:
Hi David,
This is the part I was commenting on. " Then came VSAM (and VVDS?) and VSAM
Catalogs,...". I took that comment as being Dave guessing that possibly the VVDS
came along with VSAM catalogs which I believe were a stepping stone between CVOLs and ICF
catalogs. I never worked with either CVOLs or VSAM catalogs but I was pretty sure the
VVDS came along with the ICF.
Rex
-----Original Message-----
From: IBM Mainframe Discussion List<IBM-MAIN@LISTSERV.UA.EDU> On
Behalf Of David Spiegel
Sent: Friday, May 24, 2024 8:55 AM
To:IBM-MAIN@LISTSERV.UA.EDU
Subject: [EXTERNAL] Re: VTOCs vs. catalogs
Hi Rex,
"...Followed by SMS and VVDS for non-VSAM datasets ..."
This was meant (AFAIK) to state that VVDS for Non-VSAMs came into use with
SMS-Controlled DASD Volumes.
It is also true that VVDSs were introduced with ICF Catalogs (circa 1981,
recalled and re-released in 1982).
Regards,
David
On 2024-05-24 09:44, Pommier, Rex wrote:
Didn't the VVDS come along with the ICF catalog structure?
-----Original Message-----
From: IBM Mainframe Discussion List<IBM-MAIN@LISTSERV.UA.EDU> On
Behalf Of Gibney, Dave
Sent: Thursday, May 23, 2024 10:32 PM To:IBM-MAIN@LISTSERV.UA.EDU
Subject: [EXTERNAL] Re: VTOCs vs. catalogs
All speculation on my part. One system with no DASD, you need neither.
On a system with only one, of just a few DASD volumes, a VTOC is required to
say where on the volume a dataset is and the basic attributes of PS and PDS
datasets.
Once you get to several always mounted DASSD volumes, it becomes a pain to need
to remember and specify VOLSER in the JCL.
CVOLs where an early attempt to solve this problem. Then came VSAM
(and VVDS?) and VSAM Catalogs, and somewhile later ECf/Catalogs.
Followed by SMS and VVDS for non-VSAM datasets
-----Original Message-----
From: IBM Mainframe Discussion List<IBM-MAIN@LISTSERV.UA.EDU> On
Behalf Of Mike Schwab
Sent: Thursday, May 23, 2024 8:24 PM To:IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: VTOCs vs. catalogs
[EXTERNAL EMAIL]
For the most part the catalog lets you locate your dataset no matter
which volume you put it on.
For non-vsam, that is about all that is stored, dataset
characteristics are in the VTOC.
And with non-SMS volumes you can have uncataloged datasets on DASD
or tape.
VSAM came from the Future Systems development as a complete
replacement, Lynn Wheeler has posts about that.
It was cut back to be an addition to MVS, then combined with CVOL
catalogs to ICF.
On Thu, May 23, 2024 at 9:32 PM Phil Smith III<li...@akphs.com> wrote:
I'm curious whether any of you old-timers can explain why we have
both VTOCs and catalogs. I'm guessing it comes down to (a) VTOCs
came first and catalogs were added to solve some problem (what?)
and/or (b) catalogs
were added to save some I/O and/or memory, back when a bit of those
mattered. But I'd like to understand. Anyone?
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