Need storage used explanation

Hello

Need storage used explanation
HI all ,

Examining the DBM1 resource usage with my MVS monitor , i see that
Dmd Page/Sec is 3

Dmd Page means that DB2 need a page that OS/390 has stolen , so it seems
that central storage resource is somewhat over-committed ?

But the MVS overview shows that there is still storage available .

Can you explain me where i am wrong ?

Thanks




MVS overview :


10JAN2003 11:04:53 -------- MAINVIEW WINDOW INTERFACE ----------
COMMAND ===> SCR
CURR WIN ===> 1 ALT WIN ===>
>H1 =SYSPERF===========SIC6=====*========09JAN2003==21:29:00====M
System Info......... Common Storage Use..
System Name......... SIC6 CSA Used Percentage. 42.80
SMF ID.............. SIC6 ECSA Used Percentage 54.48
Sysplex Name........ PLEX01 SQA Used Percentage. 56.89
CPU Model........... 9672 ESQA Used Percentage 87.69
MVS Release......... SP7.0.2
VM Guest............ N Defined CSA......... 2.4Mi
Defined ECSA........ 91Mi
CPU Utilization..... Defined SQA......... 1.1Mi
CPU Busy%........... 90.26 Defined ESQA........ 19Mi
MVS Busy%........... 100.00
SRM Avg CPU Busy%... 100.00 Available CSA....... 1.4Mi
Avg In and Ready.... 30.42 Available ECSA...... 41Mi
Avg Out and Ready... 0.00 Available SQA....... 483Ki
System Wkflw%....... 11.72 Available ESQA...... 2.4Mi

Hardware Utilization CSA Converted....... 0
I/O Int Rate p/s.... 1438.29 ECSA Converted...... 0
%I/O Interupts TPI.. 7.66
Chan Path Busy%..... 30.05 SQA Tracking Status. YES



DBM1 overview :

10JAN2003 11:10:49 -------- MAINVIEW WINDOW INTERFACE ---------------------
---
COMMAND ===> SCROLL ===>
PAGE
CURR WIN ===> 1 ALT WIN
===>
>W1
=EZMJOB===JINFO====SIC6=====*========09JAN2003==21:29:00====MVMVS====D====1
Timeframe... Interval
0....50..100
Jobname..... DR06DBM1 Avg Frames.. 73762 Workflow...
98.33
Step/Proc... DR06DBM1 Avg Cframes. 27405 Using Proc.
1.70
JES Number.. STC06668 Avg Eframes. 46357 Using Dev..
6.66
Terminal ID. Cframes held 31774 Total Dly..
0.14
ASID........ 106 Eframes held 40336 Processor.
0.00
Dmn......... N/A Fixed frames 1264 Device....
0.00
SC or PG #.. 6 Fixed <16M.. 12 Storage...
0.00
SrvClass.... STCH Dmd Page/Sec 3 Enqueue...
0.14
Workload.... Swp Page/Sec 0 SRM.......
0.00
%Connected.. 1.3 Avg UIC..... 246 Msg.......
0.00
Disp. Prty.. 251 SU/Sec...... 4699 Xcf.......
0.00
Owner....... SYSDSP EXCP/Sec.... 45.6 JES.......
0.00
Status...... Active Job Elpd Tm. 561:22:4 HSM.......
0.00
Last........ Active JES Queue Tm 00:00:00 Unknown....
0.00



Joel Goldstein

Re: Need storage used explanation
(in response to Hello)
I haven't used Mainview for years, and done have access.
Are you sure DMD page means stolen.... as paged to dasd, or does
it simply mean its being paged back in from expanded?
How much memory is really on your machine, central and expanded?
DBM1 is using 112 Meg of real, and 190 meg of expanded.
You can be pretty sure that between DB2, MVS, JES, and all the other
jobs in your system the real memory is all used up, and you are paging
everything
back/forth to expanded.
I think the paging rate of 3/sec (expanded) is not bad at all.

Regards,
Joel



Message text written by DB2 Data Base Discussion List
>HI all ,

Examining the DBM1 resource usage with my MVS monitor , i see that
Dmd Page/Sec is 3

Dmd Page means that DB2 need a page that OS/390 has stolen , so it seems
that central storage resource is somewhat over-committed ?

But the MVS overview shows that there is still storage available .

Can you explain me where i am wrong ?

Thanks




MVS overview :


10JAN2003 11:04:53 -------- MAINVIEW WINDOW INTERFACE ----------
COMMAND ===> SCR
CURR WIN ===> 1 ALT WIN ===>
>H1 =SYSPERF===========SIC6=====*========09JAN2003==21:29:00====M
System Info......... Common Storage Use..
System Name......... SIC6 CSA Used Percentage. 42.80
SMF ID.............. SIC6 ECSA Used Percentage 54.48
Sysplex Name........ PLEX01 SQA Used Percentage. 56.89
CPU Model........... 9672 ESQA Used Percentage 87.69
MVS Release......... SP7.0.2
VM Guest............ N Defined CSA......... 2.4Mi
Defined ECSA........ 91Mi
CPU Utilization..... Defined SQA......... 1.1Mi
CPU Busy%........... 90.26 Defined ESQA........ 19Mi
MVS Busy%........... 100.00
SRM Avg CPU Busy%... 100.00 Available CSA....... 1.4Mi
Avg In and Ready.... 30.42 Available ECSA...... 41Mi
Avg Out and Ready... 0.00 Available SQA....... 483Ki
System Wkflw%....... 11.72 Available ESQA...... 2.4Mi

Hardware Utilization CSA Converted....... 0
I/O Int Rate p/s.... 1438.29 ECSA Converted...... 0
%I/O Interupts TPI.. 7.66
Chan Path Busy%..... 30.05 SQA Tracking Status. YES



DBM1 overview :

10JAN2003 11:10:49 -------- MAINVIEW WINDOW INTERFACE
---------------------
---
COMMAND ===> SCROLL ===>
PAGE
CURR WIN ===> 1 ALT WIN
===>
>W1
=EZMJOB===JINFO====SIC6=====*========09JAN2003==21:29:00====MVMVS====D====1
Timeframe... Interval
0....50..100
Jobname..... DR06DBM1 Avg Frames.. 73762 Workflow...
98.33
Step/Proc... DR06DBM1 Avg Cframes. 27405 Using Proc.
1.70
JES Number.. STC06668 Avg Eframes. 46357 Using Dev..
6.66
Terminal ID. Cframes held 31774 Total Dly..
0.14
ASID........ 106 Eframes held 40336 Processor.
0.00
Dmn......... N/A Fixed frames 1264 Device....
0.00
SC or PG #.. 6 Fixed <16M.. 12 Storage...
0.00
SrvClass.... STCH Dmd Page/Sec 3 Enqueue...
0.14
Workload.... Swp Page/Sec 0 SRM.......
0.00
%Connected.. 1.3 Avg UIC..... 246 Msg.......
0.00
Disp. Prty.. 251 SU/Sec...... 4699 Xcf.......
0.00
Owner....... SYSDSP EXCP/Sec.... 45.6 JES.......
0.00
Status...... Active Job Elpd Tm. 561:22:4 HSM.......
0.00
Last........ Active JES Queue Tm 00:00:00 Unknown....
0.00<



Chris Blaicher

Re: Need storage used explanation
(in response to Joel Goldstein)
Interesting value for the DBM1 space is the AVERAGE UIC of 246. A page that
was just referenced has a UIC of 0 (zero). The max UIC is 255, the machine
does not keep track of higher numbers. A UIC of 246 means that it has been
a loooonnnngggg time between references to pages in that address space. The
system will steal pages with high UIC counts first, so it makes sense that
you are seeing what you see.

From this one snapshot, I would not say you are memory constrained. A
better place to look is at what the overall system paging rate is. Even
with paging going on in general, it may not be a bad thing, IF you are
meeting your service level agreements. It looks like you are running your
processor flat out, but once again, that is not necessarily a bad thing.

Chris Blaicher
BMC Software, Inc.
Austin Research Labs
10415 Morado Circle
Austin, TX 78759
512/340-6154

BMC Software, Inc. makes no representations or promises regarding the
reliability, completeness, or accuracy of the information provided in
this discussion; all readers agree not to rely on or take any action
against BMC Software in response to this information.


-----Original Message-----
From: Christophe Radier [mailto:[login to unmask email]
Sent: Friday, January 10, 2003 10:45 AM
To: [login to unmask email]
Subject: Need storage used explanation


HI all ,

Examining the DBM1 resource usage with my MVS monitor , i see that
Dmd Page/Sec is 3

Dmd Page means that DB2 need a page that OS/390 has stolen , so it seems
that central storage resource is somewhat over-committed ?

But the MVS overview shows that there is still storage available .

Can you explain me where i am wrong ?

Thanks




MVS overview :


10JAN2003 11:04:53 -------- MAINVIEW WINDOW INTERFACE ----------
COMMAND ===> SCR
CURR WIN ===> 1 ALT WIN ===>
>H1 =SYSPERF===========SIC6=====*========09JAN2003==21:29:00====M
System Info......... Common Storage Use..
System Name......... SIC6 CSA Used Percentage. 42.80
SMF ID.............. SIC6 ECSA Used Percentage 54.48
Sysplex Name........ PLEX01 SQA Used Percentage. 56.89
CPU Model........... 9672 ESQA Used Percentage 87.69
MVS Release......... SP7.0.2
VM Guest............ N Defined CSA......... 2.4Mi
Defined ECSA........ 91Mi
CPU Utilization..... Defined SQA......... 1.1Mi
CPU Busy%........... 90.26 Defined ESQA........ 19Mi
MVS Busy%........... 100.00
SRM Avg CPU Busy%... 100.00 Available CSA....... 1.4Mi
Avg In and Ready.... 30.42 Available ECSA...... 41Mi
Avg Out and Ready... 0.00 Available SQA....... 483Ki
System Wkflw%....... 11.72 Available ESQA...... 2.4Mi

Hardware Utilization CSA Converted....... 0
I/O Int Rate p/s.... 1438.29 ECSA Converted...... 0
%I/O Interupts TPI.. 7.66
Chan Path Busy%..... 30.05 SQA Tracking Status. YES



DBM1 overview :

10JAN2003 11:10:49 -------- MAINVIEW WINDOW INTERFACE ---------------------
---
COMMAND ===> SCROLL ===>
PAGE
CURR WIN ===> 1 ALT WIN
===>
>W1
=EZMJOB===JINFO====SIC6=====*========09JAN2003==21:29:00====MVMVS====D====1
Timeframe... Interval
0....50..100
Jobname..... DR06DBM1 Avg Frames.. 73762 Workflow...
98.33
Step/Proc... DR06DBM1 Avg Cframes. 27405 Using Proc.
1.70
JES Number.. STC06668 Avg Eframes. 46357 Using Dev..
6.66
Terminal ID. Cframes held 31774 Total Dly..
0.14
ASID........ 106 Eframes held 40336 Processor.
0.00
Dmn......... N/A Fixed frames 1264 Device....
0.00
SC or PG #.. 6 Fixed <16M.. 12 Storage...
0.00
SrvClass.... STCH Dmd Page/Sec 3 Enqueue...
0.14
Workload.... Swp Page/Sec 0 SRM.......
0.00
%Connected.. 1.3 Avg UIC..... 246 Msg.......
0.00
Disp. Prty.. 251 SU/Sec...... 4699 Xcf.......
0.00
Owner....... SYSDSP EXCP/Sec.... 45.6 JES.......
0.00
Status...... Active Job Elpd Tm. 561:22:4 HSM.......
0.00
Last........ Active JES Queue Tm 00:00:00 Unknown....
0.00








Chris Blaicher

Re: Need storage used explanation
(in response to Chris Blaicher)
One thing I forgot to mention in my first post was that the system will
attempt to maintain a pool of available pages so that it can satisfy page-in
requests without having to do a page-out first to free a page. This is why
you will often see paging while there are free pages in the system. It just
wants a few more free.

If your UIC count goes down AND you see additional paging, THEN get
interested. I would not panic at all, just start to watch the numbers AND
watch your DB2 response times.

Every performance evaluation is complex and unique. Any advice I give is
based on a lot of assumptions and a limited amount of information. The two
things I used to watch the most were, is the system meeting its performance
objectives; and, what are the performance trends. Not meeting the
performance objects is cause for panic. Watching the trends will hopefully
give you enough lead time to do something about the cause before it is time
to panic.

Chris Blaicher
BMC Software, Inc.
Austin Research Labs
10415 Morado Circle
Austin, TX 78759
512/340-6154

BMC Software, Inc. makes no representations or promises regarding the
reliability, completeness, or accuracy of the information provided in this
discussion; all readers agree not to rely on or take any action against BMC
Software in response to this information.



Cathy Taddei

Re: Need storage used explanation
(in response to Chris Blaicher)
Hi Christophe. Are you getting storage available figures from screen
FRMINFO? On my system, if I add up the Central storage averages, they add
up to more central storage than we have on the system, even if I exclude the
so-called "available" pages. But then if I add the "total" column to the
"available" column, it adds up to less storage than I have configured. So I
don't trust these numbers, and I would imagine they are hard to estimate,
anyway. It's been a very long time since my MVS classes, but I believe the
available frame queue contains any number of active pages that are
nevertheless stealable; maybe Mainview counts these as "available."

A lot depends on your workload, but I feel that the only good page rate is
0, especially in DBM1. If 3 pages/sec were your high water mark for paging,
I wouldn't give it another thought, but if it creeps up for extended
periods, I would look for the cause, and perhaps look at reducing my demands
on real storage. Of course, it would be a mistake to tune your system for
storage alone and disregard CPU and I/O, and you have to consider your
entire workload.

Cathy Taddei

-----Original Message-----
From: Christophe Radier [mailto:[login to unmask email]
Sent: Friday, January 10, 2003 8:45 AM
To: [login to unmask email]
Subject: Need storage used explanation


HI all ,

Examining the DBM1 resource usage with my MVS monitor , i see that
Dmd Page/Sec is 3

Dmd Page means that DB2 need a page that OS/390 has stolen , so it seems
that central storage resource is somewhat over-committed ?

But the MVS overview shows that there is still storage available .

Can you explain me where i am wrong ?

Thanks




MVS overview :

<snipped for length>

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