SDSP?
Isn't it a feature of DFSMShsm?
We're using it for ML1 purposes, I'm not aware of any other purpose,
including "ML0".
BTW: It is not my problem, I just heard about it. In my opinion it would
be wise to review the application in order to reduce the number of
datasets created.
--
Radoslaw Skorupka
Lodz, Poland
W dniu 2018-01-13 o 21:56, Mike Schwab pisze:
z/OS does have Small Data Set Packing. Puts datasets under your exit
size limit into a VSAM KSDS. For another storage pool, we did run
into problems with not enough entries in the VTOC, so we created
smaller volumes with large VTOCs.
On Sat, Jan 13, 2018 at 2:19 PM, R.S. <[email protected]> wrote:
Ron,
While your solution can keep "small" datasets away from EAS, it is not a
solution for a need I described.
I mean a scenarion when many thousands of relatively small datasets need to
be kept on disk. Colleague of mine administer a system, where ~200 000
datasets are created during EOD.
Of course when we talk about big storage needs it's usually not-so-many
datasets, but big or huge ones.
Last, but not least, we have limited choice - up to 64(-256) non-EAV volumes
or bigger EAV volumes (with the same limit for quantity).
Regards
--
Radoslaw Skorupka
Lodz, Poland
W dniu 2018-01-13 o 19:02, Ron hawkins pisze:
Radoslaw,
That's why you can change the threshold for the track allocation area.
DCOLLECT and PROC UNIVARIATE will probably give you all the guidance you
need. DCOLLECT does not have the primary space allocation size so this code
is not 100% accurate. It is good enough to give some guidance.
I executed this against one of our general purpose lab systems, and this
is the CMA waste estimate with break point value at 5, 10 and 20 cylinders.
EAV Breakpointvalue 10 Cylinders
Total Used Cylinders 7516066.07911661
Total Wasted Cylinders 610787.607878009
Percent Wasted CMA 8.1%
EAV Breakpointvalue 5 Cylinders
Total Used Cylinders 7516066.07911661
Total Wasted Cylinders 783635.165880735
Percent Wasted CMA 10.4%
EAV Breakpointvalue 20 Cylinders
Total Used Cylinders 7516066.07911661
Total Wasted Cylinders 309321.636811143
Percent Wasted CMA 4.1%
You could use SAS code like this to come up with a good starting point
for your shop when you go EAV.
options obs=max bufno=256 nosource2 nomacrogen nosymbolgen nomlogic
nomprint sortsize=6G msglevel=i;
goptions reset=all;
%let BPV=20;
Title1 "EAV Breakpoint Value &BPV Cylinders"; ***
Main Output Title ;
FILENAME DCOLLECT FTP (
"MY.DCOL'"
)
USER='myuid' HOST='111.222.333.444' DEBUG
S370VS RCMD='SITE RDW' LRECL=32760
PASS='mypw';
proc datasets lib=pdb kill noprint;
run;quit;
proc datasets lib=work kill noprint;
run;quit;
%include sourclib(typedcol);
run;
data dcolsp;
set dcoldset;
usedcyl=dcdusesp/(15*56664);
if usedcyl>&BPV then wastecyl=mod(usedcyl,21);
output;return;
run;
title2 "Data set size distribution in Cylinders";
proc univariate data=dcolsp;
var usedcyl;
histogram;
run;
title2 "Cylinder Managed Area - Data set size distribution in Cylinders";
proc univariate data=dcolsp;
where usedcyl>&bpv;
var usedcyl;
histogram;
run;
proc summary data=dcolsp nway;
var usedcyl wastecyl;
output out=dcolsum
sum=
;
run;
data _null_;
set dcolsum;
pctwaste=wastecyl/usedcyl;
put "EAV Breakpointvalue &BPV Cylinders"
/ "Total Used Cylinders " usedcyl best16.
/ "Total Wasted Cylinders " wastecyl best16.
/ "Percent Wasted CMA " pctwaste
percent16.1
;
run;
-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On
Behalf Of R.S.
Sent: Friday, January 12, 2018 5:48 AM
To: [email protected]
Subject: Re: [IBM-MAIN] AW: Re: Number of Cylinders per Volume
W dniu 2018-01-12 o 13:15, Tom Marchant pisze:
On Fri, 12 Jan 2018 01:32:07 +0100, R.S. wrote:
BTW: an "awful waste of storage" is MCU on EAS which is 21 cyl. (315
trk). It is much more than 4kB and more than 4MB.
Not such a big deal for very large data sets, which are the most
appropriate ones to go into the cylinder-managed space. When you have
a quarter of a million cylinders, allocating space on increments of 21
cylinders isn't so bad, IMO.
Of course. However sometimes people need a lot of not-so-big datasets.
For ~1000 cyl datasets average lost is ~1% ( (21/2)/1000 ), but for 50 cyl
datasets is ~20%.
--
Radoslaw Skorupka
Lodz, Poland
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