Not surprising. IAM replaces VSAM, including
physical I/O to the file(s), along with better buffering and lookaside.
VSAM can have internally compressed records (like
RMF III data stores do), but the application is
responsible to processing the by the application data into a usable form.
In the past, I worked with an application that
included their own access method that employed
internally compressed records that included
uncompressed records upwards of 3MB in size
(similar in size to some of the reassembled long
RMF records). This access method used KSDS VSAM
and allowed sequential or keyed access to concatenated VSAM files.
Michael
At 02:26 PM 4/16/2024, rpinion865 wrote:
orm usable by the application
Curious, do you use IAM for Hogan
applications? My previous life did, and the
applications group was very satisfied with the
IAM performance vs. native VSAM. However, we
had to impress on them, that periodic reorgs
were more necessary for IAM, than under
VSAM. And, we found out that ADRDSSU
dump/restore of VSAM was what was being used to
perform VSAM reorgs, as opposed to IDCAMS REPRO, DELETE,
DEFINE, REPRO. Guess what, ADRDSSU sees an IAM dataset as extended format PS!
Sent with Proton Mail secure email.
On Tuesday, April 16th, 2024 at 3:02 PM, Jousma,
David <000001a0403c5dc1-dmarc-requ...@listserv.ua.edu> wrote:
> Thanks for that. We do have IAM here, well
open a ticket with BMC asking about support. I
was just doubting since it presents to the OS as a VSAM dataset.
>
> We were hoping to make ZEDC inclusive as in
everyone gets it to reap the space reduction,
and job performance improvements and that the
OS would decide for us if a particular dataset
that has the DATACLAS assigned to it would just
ignore, but that wont be the case.
>
> I have the ability to code ZEDC_preferred or
ZEDC-Required. Required will actually fail the
allocation, which I dont want to either, but I
also dont want to use non-accelerated compression either.
>
> So, now as you pointed out, well have to
approach ZEDC as exclusive and only opt-in
file types that are supported like GDGs for
sure. We may roll the dice on all PS, exempting
temp datasets and ISPF work datasets, and more
as we stumble upon other incompatibilities.
>
> With knowing the technical details, I think
IBM missed the boat here. ZEDC ought to be a
drop-in replacement for compression, period. I
can specify COMPACTION YES for VSAM files but ZEDC wont touch them. Why?
>
> Dave Jousma
> Vice President | Director, Technology Engineering
>
>
>
>
>
> From: IBM Mainframe Discussion List
IBM-MAIN@LISTSERV.UA.EDU on behalf of
rpinion865 0000042a019916dd-dmarc-requ...@listserv.ua.edu
>
> Date: Tuesday, April 16, 2024 at 2:25â¯PM
> To: IBM-MAIN@LISTSERV.UA.EDU IBM-MAIN@LISTSERV.UA.EDU
>
> Subject: Re: Anyone exploiting ZEDC?
> At my previous life, we were using BMC's IAM
VSAM interface. I think IAM could use zEDC. But
I was told by then IDP support, that IAM's
internal compression was Moe (as in Moe Howard)
better than even zEDC. Regarding coding for PS datasets
>
>
> At my previous life, we were using BMC's IAM
VSAM interface. I think IAM could use zEDC. But
I was told by then IDP support, that IAM's
internal compression was Moe (as in Moe Howard) better than even zEDC.
>
>
>
> Regarding coding for PS datasets opened
in/out, I think DAF will show how a PS dataset
is being opened. We chose to use zEDC
compression for new,catlg,delete GDGs because
we were very confident that no one was going to
process that combination as in/out.
>
> And does not the IBM zBNA tool highlight good
candidates? We did not want to clutter up our
SMS ACS DC routines with too many actions to
put certain PS datasets into zEDC compression.
But in the end, we did put certain large PS,
not opened in/out, datasets in the ACS DC routine.
>
>
>
>
>
>
>
>
>
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