Track size CA rather than cylinder was Re: Freeing up space in a VSAM file

[Clark Morris]

On 15 Mar 2016 07:55:41 -0700, in bit.listserv.ibm-main Mike Schwab
wrote:

>On our HSM MCDS, BCDS, etc, we have 0 for the secondary extent.
>If we specified TRACK(5 1) so we get 1 track as the Control Area,
>1. How much would the Index size go up?  15X?
>2. Wouldn't CAs be reused a lot more frequently, since you only have
>to get 1 track empty instead of 15?
>3. Which would be better for an end user?
>4. How would throughput be affected?

I would definitely not go for this.  With a good choice of data and
index CI sizes, the indexes for a cylinder sized CA should fit in one
index CI.  For the size of the data set you should have no more than 3
index (2 plus the sequence set) levels.  With a track size CA you will
have at least 4 index levels.

Clark Morris   
>
>On Tue, Mar 15, 2016 at 6:07 AM, John Eells  wrote:
>> Norbert Friemel wrote:
>> 
>>>
>>>
>>> CA_RECLAIM?
>>> http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d4a0/2.5.3.3
>>
>> 
>>
>> Norbert beat me to it (smile).  The key to this being useful is that you
>> have empty CAs to reclaim.  One could have a pathological application that
>> left one record per CA behind after deleting the rest, so that no CAs ever
>> emptied out to be reclaimed, for example.  Or, one could have an even *more*
>> pathological application that wrote a lot of records into specific key
>> ranges, deleted them all (causing reclaims) and then rewrote a lot of
>> records into the same key ranges, causing CA reclaim/CA allocation thrashing
>> to the detriment of performance.
>>
>> That said, it's very likely that using CA Reclaim will get you out of the
>> reorg business, permanently, with no ill effects, for all of your KSDSs.  CA
>> Reclaim is available on all supported releases now, but I have heard of only
>> one pathological application so far.  Of course, it was one of ours here at
>> IBM.  (You can't make this stuff up.)
>>
>> --
>> John Eells
>> IBM Poughkeepsie
>> ee...@us.ibm.com
>>
>>
>> --
>> For IBM-MAIN subscribe / signoff / archive access instructions,
>> send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN

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Re: Freeing up space in a VSAM file

[Steve Beaver]

If you have 1 MCDS, make 2 out of that one.  That will give you 2 with the 
former size.

The BCDS depending on how full it is increase the size 50%

Steve  

-Original Message-
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf 
Of Mike Schwab
Sent: Tuesday, March 15, 2016 9:56 AM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: Freeing up space in a VSAM file

On our HSM MCDS, BCDS, etc, we have 0 for the secondary extent.
If we specified TRACK(5 1) so we get 1 track as the Control Area, 1. How 
much would the Index size go up?  15X?
2. Wouldn't CAs be reused a lot more frequently, since you only have to get 1 
track empty instead of 15?
3. Which would be better for an end user?
4. How would throughput be affected?

On Tue, Mar 15, 2016 at 6:07 AM, John Eells <ee...@us.ibm.com> wrote:
> Norbert Friemel wrote:
> 
>>
>>
>> CA_RECLAIM?
>> http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d4a0/2
>> .5.3.3
>
> 
>
> Norbert beat me to it (smile).  The key to this being useful is that 
> you have empty CAs to reclaim.  One could have a pathological 
> application that left one record per CA behind after deleting the 
> rest, so that no CAs ever emptied out to be reclaimed, for example.  
> Or, one could have an even *more* pathological application that wrote 
> a lot of records into specific key ranges, deleted them all (causing 
> reclaims) and then rewrote a lot of records into the same key ranges, 
> causing CA reclaim/CA allocation thrashing to the detriment of performance.
>
> That said, it's very likely that using CA Reclaim will get you out of 
> the reorg business, permanently, with no ill effects, for all of your 
> KSDSs.  CA Reclaim is available on all supported releases now, but I 
> have heard of only one pathological application so far.  Of course, it 
> was one of ours here at IBM.  (You can't make this stuff up.)
>
> --
> John Eells
> IBM Poughkeepsie
> ee...@us.ibm.com
>
>
> --
> For IBM-MAIN subscribe / signoff / archive access instructions, send 
> email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN



--
Mike A Schwab, Springfield IL USA
Where do Forest Rangers go to get away from it all?

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Re: Freeing up space in a VSAM file

[Staller, Allan]

I have been using CA-RECLAIM since 20012 for both dfHSM and dfRMM.  No problems 
or worries. I highly recommend it.
As a matter of fact it is a shop-wide default here.

SET CA-RECLAIM(DATACLAS) in IGDSMS00. The default for each DATACLAS is 
CA-RECLAIM(YES).

One caveat. You don’t get the benefit until the clusters are redefined.

HTH,


I don't want to create a gorilla-survey here, but I would be interested in 
hearing some user experience with CA Reclaim. I first heard about it at SHARE 
several years ago, but we have yet to dip a toe in the crocodile pond. It would 
be most beneficial for system utility clusters like HSM and RMM, but that's the 
last arena I would want to encounter a problem. 


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Re: Freeing up space in a VSAM file

[Jesse 1 Robinson]

I don't want to create a gorilla-survey here, but I would be interested in 
hearing some user experience with CA Reclaim. I first heard about it at SHARE 
several years ago, but we have yet to dip a toe in the crocodile pond. It would 
be most beneficial for system utility clusters like HSM and RMM, but that's the 
last arena I would want to encounter a problem. 

.
.
.
J.O.Skip Robinson
Southern California Edison Company
Electric Dragon Team Paddler 
SHARE MVS Program Co-Manager
323-715-0595 Mobile
626-302-7535 Office
robin...@sce.com

-Original Message-
From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf 
Of John Eells
Sent: Tuesday, March 15, 2016 4:08 AM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: (External):Re: Freeing up space in a VSAM file

Norbert Friemel wrote:

>
> CA_RECLAIM? 
> http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d4a0/2.
> 5.3.3


Norbert beat me to it (smile).  The key to this being useful is that you have 
empty CAs to reclaim.  One could have a pathological application that left one 
record per CA behind after deleting the rest, so that no CAs ever emptied out 
to be reclaimed, for example.  Or, one could have an even *more* pathological 
application that wrote a lot of records into specific key ranges, deleted them 
all (causing reclaims) and then rewrote a lot of records into the same key 
ranges, causing CA reclaim/CA allocation thrashing to the detriment of 
performance.

That said, it's very likely that using CA Reclaim will get you out of the reorg 
business, permanently, with no ill effects, for all of your KSDSs.  CA Reclaim 
is available on all supported releases now, but I have heard of only one 
pathological application so far.  Of course, it was one of ours here at IBM.  
(You can't make this stuff up.)

-- 
John Eells
IBM Poughkeepsie
ee...@us.ibm.com


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Re: Freeing up space in a VSAM file

[Mike Schwab]

On our HSM MCDS, BCDS, etc, we have 0 for the secondary extent.
If we specified TRACK(5 1) so we get 1 track as the Control Area,
1. How much would the Index size go up?  15X?
2. Wouldn't CAs be reused a lot more frequently, since you only have
to get 1 track empty instead of 15?
3. Which would be better for an end user?
4. How would throughput be affected?

On Tue, Mar 15, 2016 at 6:07 AM, John Eells  wrote:
> Norbert Friemel wrote:
> 
>>
>>
>> CA_RECLAIM?
>> http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d4a0/2.5.3.3
>
> 
>
> Norbert beat me to it (smile).  The key to this being useful is that you
> have empty CAs to reclaim.  One could have a pathological application that
> left one record per CA behind after deleting the rest, so that no CAs ever
> emptied out to be reclaimed, for example.  Or, one could have an even *more*
> pathological application that wrote a lot of records into specific key
> ranges, deleted them all (causing reclaims) and then rewrote a lot of
> records into the same key ranges, causing CA reclaim/CA allocation thrashing
> to the detriment of performance.
>
> That said, it's very likely that using CA Reclaim will get you out of the
> reorg business, permanently, with no ill effects, for all of your KSDSs.  CA
> Reclaim is available on all supported releases now, but I have heard of only
> one pathological application so far.  Of course, it was one of ours here at
> IBM.  (You can't make this stuff up.)
>
> --
> John Eells
> IBM Poughkeepsie
> ee...@us.ibm.com
>
>
> --
> For IBM-MAIN subscribe / signoff / archive access instructions,
> send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN



-- 
Mike A Schwab, Springfield IL USA
Where do Forest Rangers go to get away from it all?

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Re: Freeing up space in a VSAM file

[John Eells]

Norbert Friemel wrote:



CA_RECLAIM? 
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d4a0/2.5.3.3



Norbert beat me to it (smile).  The key to this being useful is that you 
have empty CAs to reclaim.  One could have a pathological application 
that left one record per CA behind after deleting the rest, so that no 
CAs ever emptied out to be reclaimed, for example.  Or, one could have 
an even *more* pathological application that wrote a lot of records into 
specific key ranges, deleted them all (causing reclaims) and then 
rewrote a lot of records into the same key ranges, causing CA reclaim/CA 
allocation thrashing to the detriment of performance.


That said, it's very likely that using CA Reclaim will get you out of 
the reorg business, permanently, with no ill effects, for all of your 
KSDSs.  CA Reclaim is available on all supported releases now, but I 
have heard of only one pathological application so far.  Of course, it 
was one of ours here at IBM.  (You can't make this stuff up.)


--
John Eells
IBM Poughkeepsie
ee...@us.ibm.com

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Re: Freeing up space in a VSAM file

[Norbert Friemel]

On Tue, 15 Mar 2016 07:57:41 +0200, Steff Gladstone wrote:

>Greetings,
>
>We have a KSDS file that gradually fills up with records.  After deleting a
>large number of records we still received nonzero response codes when
>trying to add new records indicating that there is no available space in
>the file.  We have no alternative but to disable access to the file and
>reorganize it, causing quite a disruption to operations.
>
>Presumably this is because of the way the indexes are organized.  Any
>advice?  What parameters do you suggest we "play" with to ameliorate the
>situation?
>

CA_RECLAIM? 
http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/dgt2d4a0/2.5.3.3

Norbert Friemel

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Re: Freeing up space in a VSAM file

[Elardus Engelbrecht]

Steff Gladstone wrote:

>We have a KSDS file that gradually fills up with records.  After deleting a 
>large number of records we still received nonzero response codes when trying 
>to add new records indicating that there is no available space in the file.  
>We have no alternative but to disable access to the file and reorganize it, 
>causing quite a disruption to operations.

>Presumably this is because of the way the indexes are organized.  Any advice?  
>What parameters do you suggest we "play" with to ameliorate the situation?

Please post the results of the LISTC of that VSAM dataset. If you can show the 
ATTRIBUTES, STATISTICS, ALLOCATION and the VOLUME details, I think the IBM-MAIN 
members can see what the problem is.

Groete / Greetings
Elardus Engelbrecht

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Freeing up space in a VSAM file

[Steff Gladstone]

Greetings,

We have a KSDS file that gradually fills up with records.  After deleting a
large number of records we still received nonzero response codes when
trying to add new records indicating that there is no available space in
the file.  We have no alternative but to disable access to the file and
reorganize it, causing quite a disruption to operations.

Presumably this is because of the way the indexes are organized.  Any
advice?  What parameters do you suggest we "play" with to ameliorate the
situation?

Thanks in advance,
Steff Gladstone

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