RE: [IBM-MAIN] Data compression (was:RE: CA-TopSecret SP1 (and above) CICS SIGNON Problem)
- From: Ron.Hawkins@xxxxxxxxxxxx (Ron Hawkins)
- Date: 18 Jun 2007 11:57:27 -0700
John,
One reason for using compression is when you are running Synchronous
Remote Copy over DWDM or other media that do not support network
compression.
Some selective application of DFSMS or similar compression to some key
files can offset the performance hit that occurs with Synchronous Remote
Copy.
In Singapore many years ago I did this when implanting SRDF and actually
improved the batch run time as the benefit of selective compression was
greater than the write hit of Synchronous Remote Copy.
Ron Hawkins
Senior Performance Consultant
Product Performance Management
GSSD - Technical Operations
Hitachi Data Systems
750 Central Expressway
Santa Clara. Ca. 95050-2627
United States
Desk: +1 408 720 8893
Mobile: +TBD
Fax: +TBD
ron.hawkins@xxxxxxx
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@xxxxxxxxxxxx
Behalf Of McKown, John
Sent: Monday, June 18, 2007 11:27 AM
To: IBM-MAIN@xxxxxxxxxxx
Subject: [IBM-MAIN] Data compression (was:RE: CA-TopSecret SP1 (and
above) CICS SIGNON Problem)
-----Original Message-----
From: IBM Mainframe Discussion List
[mailto:IBM-MAIN@xxxxxxxxxxx] On Behalf Of Kelman, Tom
Sent: Monday, June 18, 2007 1:18 PM
To: IBM-MAIN@xxxxxxxxxxx
Subject: Re: CA-TopSecret SP1 (and above) CICS SIGNON Problem
We were informed by CA that the problem has to do with some algorithm
they use to "compress" the last date accessed. It is date specific.
They next time it would occur if not fixed is January 6, 2007. Wasn't
the "compression" of dates what got us all into trouble with Y2K. Why
in the world are they doing that?
Tom Kelman
Commerce Bank of Kansas City
(816) 760-7632
The usual cannot-learn-from-the-past reason. Compression costs ongoing
CPU, which is now generally more expensive than memory. But there is
still some resistance to "wasting" memory and/or DASD space. It made
sense in the past. It is senseless now.
BTW - somewhat on the same page, why should anybody use any kind of
compression which uses CPU today? I.e. why do people use DFSMS
compression or some other OEM compression such as BMC's Data
Accelerator? We use the latter, but mainly because we needed to store
more records within the then-existant 4GiB barrier on VSAM.
Unfortunately, the then-management then mandated using it on most
everything in order to defer a DASD upgrade. Now, we are stuck with it
and it is becoming an administrative nightmare. We "compress" files
which then get messages about the files not being compressable because
there exists an alternate index field towards the end of the record.
Sheesh.
--
John McKown
Senior Systems Programmer
HealthMarkets
Keeping the Promise of Affordable Coverage
Administrative Services Group
Information Technology
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- From: McKown, John
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