DB2 for z/OS V8 - compressing SPT01

Jim McAlpine

DB2 for z/OS V8 - compressing SPT01
I'm looking to do a reorg with COMPRESS_SPT01=YES. The DB2 subsystem in
question currently has 2 x SPT01 datasets but after compression I'm certain
it will fit into one, given that I allocate enough space. Do I have to
allocate 2 x shadow datasets or just the one.

Jim McAlpine

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Howard Monical

Re: DB2 for z/OS V8 - compressing SPT01
(in response to Jim McAlpine)
I allocated the same number of shadow datasets as SPT01 datasets. We
saw about an 80% compression rate.



Howard Monical

DB2 Product Support

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From: IDUG DB2-L [mailto:[login to unmask email] On Behalf Of Jim McAlpine
Sent: Friday, January 21, 2011 9:52 AM
To: [login to unmask email]
Subject: [DB2-L] DB2 for z/OS V8 - compressing SPT01



I'm looking to do a reorg with COMPRESS_SPT01=YES. The DB2 subsystem in
question currently has 2 x SPT01 datasets but after compression I'm
certain it will fit into one, given that I allocate enough space. Do I
have to allocate 2 x shadow datasets or just the one.



Jim McAlpine



________________________________

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_____________________________________________________________________
* IDUG EMEA * Prague, Czech Republic * 14-18 November 2011 * http://IDUG.ORG/EMEA *
* If you are going to attend only one conference this year, this is it! *
** The most DB2 technical sessions of any conference
** Access IBM experts and developers
_____________________________________________________________________

If you need to change settings, http://www.idug.org/cgi-bin/wa?A0=DB2-L is the home of IDUG's Listserv

Jim Tonchick

Re: DB2 for z/OS V8 - compressing SPT01
(in response to Howard Monical)
It depends. Run DSN1COMP using a full image copy of SPT01 to see what amount of compression you can expect. Use that percentage and calculate to new size for the compressed SPT01. Don't forget to leave a generous amount of free space, say half of the calculated compressed size. Allocate a single shadow SPT01 and run your reorg. One thing to remember on subsequent reorgs make sure that you have a large enough space allocation for the SYSREC dataset used during the reorg. It contains uncompressed data.


Jim Tonchick


-----Original Message-----
From: Jim McAlpine <[login to unmask email]>
To: DB2-L <[login to unmask email]>
Sent: Fri, Jan 21, 2011 9:52 am
Subject: [DB2-L] DB2 for z/OS V8 - compressing SPT01


I'm looking to do a reorg with COMPRESS_SPT01=YES. The DB2 subsystem in question currently has 2 x SPT01 datasets but after compression I'm certain it will fit into one, given that I allocate enough space. Do I have to allocate 2 x shadow datasets or just the one.

Jim McAlpine



The IDUG DB2-L Listserv is only part of your membership in IDUG. If you are not already an IDUG member, please register here.


_____________________________________________________________________
* IDUG EMEA * Prague, Czech Republic * 14-18 November 2011 * http://IDUG.ORG/EMEA *
* If you are going to attend only one conference this year, this is it! *
** The most DB2 technical sessions of any conference
** Access IBM experts and developers
_____________________________________________________________________

If you need to change settings, http://www.idug.org/cgi-bin/wa?A0=DB2-L is the home of IDUG's Listserv

Mike Bell

Re: DB2 for z/OS V8 - compressing SPT01
(in response to Jim Tonchick)
Ack, SPT01 compression is NOT standard DB2 compression. What it does is
turn on VSAM Z/os compression which is a whole different animal than DB2
compression. Does NOT have a custom compression dictionary. Does NOT
return compressed rows to the bufferpool. Read the PTF very carefully and
then proceed.

Mike
HLS Technologies

-----Original Message-----
From: IDUG DB2-L [mailto:[login to unmask email] On Behalf Of [login to unmask email]
Sent: Friday, January 21, 2011 10:38 PM
To: [login to unmask email]
Subject: Re: [DB2-L] DB2 for z/OS V8 - compressing SPT01

It depends. Run DSN1COMP using a full image copy of SPT01 to see what
amount of compression you can expect. Use that percentage and calculate to
new size for the compressed SPT01. Don't forget to leave a generous amount
of free space, say half of the calculated compressed size. Allocate a
single shadow SPT01 and run your reorg. One thing to remember on subsequent
reorgs make sure that you have a large enough space allocation for the
SYSREC dataset used during the reorg. It contains uncompressed data.


Jim Tonchick


-----Original Message-----
From: Jim McAlpine <[login to unmask email]>
To: DB2-L <[login to unmask email]>
Sent: Fri, Jan 21, 2011 9:52 am
Subject: [DB2-L] DB2 for z/OS V8 - compressing SPT01


I'm looking to do a reorg with COMPRESS_SPT01=YES. The DB2 subsystem in
question currently has 2 x SPT01 datasets but after compression I'm certain
it will fit into one, given that I allocate enough space. Do I have to
allocate 2 x shadow datasets or just the one.

Jim McAlpine

________________________________

Independent, not-for-profit, User Run - the IDUG difference!
< http://www.idug.org/ > The IDUG DB2-L Listserv is only part of your
membership in IDUG. If you are not already an IDUG member, please register
here. < http://www.idug.org/register >

________________________________


Independent, not-for-profit, User Run - the IDUG difference!
< http://www.idug.org >

The IDUG DB2-L Listserv is only part of your membership in IDUG. If you are
not already an IDUG member, please register here.
< http://www.idug.org/register >

_____________________________________________________________________
* IDUG North America * Anaheim, California * May 2-6 2011 * http://IDUG.ORG/NA *
* Your only source for independent, unbiased, and trusted DB2 information. *
** The best DB2 technical sessions in the world
** Independent, not-for-profit, User Run - the IDUG difference!
_____________________________________________________________________

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Jim McAlpine

Re: DB2 for z/OS V8 - compressing SPT01
(in response to Mike Bell)
On Sat, Jan 22, 2011 at 2:50 PM, Mike Bell <[login to unmask email]> wrote:

> Ack, SPT01 compression is NOT standard DB2 compression. What it does is
> turn on VSAM Z/os compression which is a whole different animal than DB2
> compression. Does NOT have a custom compression dictionary. Does NOT
> return compressed rows to the bufferpool. Read the PTF very carefully and
> then proceed.
>
> Mike
> HLS Technologies
>
>
>

I allocated both SPT01 datasets and did the reorg which saved 75% of the
space. I can see from a listcat that the second dataset has a HWM of zero
so is not being used. Just out of curiosity, is there a command I can use
to see which SPT01 datasets are in use.

Jim McAlpine

_____________________________________________________________________
* IDUG North America * Anaheim, California * May 2-6 2011 * http://IDUG.ORG/NA *
* Your only source for independent, unbiased, and trusted DB2 information. *
** The most DB2 technical sessions of any conference
** Access IBM experts and developers
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Roy Boxwell

Re: DB2 for z/OS V8 - compressing SPT01
(in response to Jim McAlpine)
not that I am aware of...I just do what you did (I use IDCAMS) and see if
it has been "used" - If not then I delete the dataset(s) as DB2 does *not*
expect it to be "there" when it comes time to goto a second dataset
(unless of course you have a user defined dataset then you must pre alloc
the 2..3..4.. datasets...ah the joys of pre DB2 10 DB2... :) )

Roy Boxwell
SOFTWARE ENGINEERING GMBH
-Product Development-
Robert-Stolz-Straße 5
40470 Düsseldorf/Germany
Tel. +49 (0)211 96149-675
Fax +49 (0)211 96149-32
Email: [login to unmask email]
http://www.seg.de

Software Engineering GmbH
Amtsgericht Düsseldorf, HRB 37894
Geschäftsführung: Gerhard Schubert



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Re: [DB2-L] DB2 for z/OS V8 - compressing SPT01






On Sat, Jan 22, 2011 at 2:50 PM, Mike Bell <[login to unmask email]> wrote:
Ack, SPT01 compression is NOT standard DB2 compression. What it does is
turn on VSAM Z/os compression which is a whole different animal than DB2
compression. Does NOT have a custom compression dictionary. Does NOT
return compressed rows to the bufferpool. Read the PTF very carefully and
then proceed.

Mike
HLS Technologies



I allocated both SPT01 datasets and did the reorg which saved 75% of the
space. I can see from a listcat that the second dataset has a HWM of zero
so is not being used. Just out of curiosity, is there a command I can use
to see which SPT01 datasets are in use.

Jim McAlpine



The IDUG DB2-L Listserv is only part of your membership in IDUG. If you
are not already an IDUG member, please register here.

_____________________________________________________________________
* IDUG North America * Anaheim, California * May 2-6 2011 * http://IDUG.ORG/NA *
* Your only source for independent, unbiased, and trusted DB2 information. *
** The most DB2 technical sessions of any conference
** Access IBM experts and developers
_____________________________________________________________________

If you need to change settings, http://www.idug.org/cgi-bin/wa?A0=DB2-L is the home of IDUG's Listserv