We are working with Tivoli/IBM right now on an unrelated problem and they
have indicated to us that our cache hit should be above 98%.  We are in the
process of making changes to our region size to attempt to address this.
TSM server running on OS/390 2.10 db 37.8Gb 50% utilized. One thing that we
are being told is that a region of '0M' is not a good fit for TSM on this
platform. we are going to be testing region ' 512M ' bufpoolsize 225280.

 Our current cache hit % is 97.69.

 Brian


Brian L. Nick
Systems Technician - Storage Solutions
The Phoenix Companies Inc.
100 Bright Meadow Blvd
Enfield CT. 06082-1900

E-MAIL:  Brian.Nick AT phoenixwm DOT com
PHONE:   (860)403-2281



                                                                                
                                                       
                      "KEN HORACEK"                                             
                                                       
                      <KHORACEK@INCSYS         To:       ADSM-L AT VM.MARIST 
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                      T.EDU>                                                    
                                                       
                                                                                
                                                       
                                                                                
                                                       
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No experience.  I fact I'm learning from your experience.  While you say

"from my training at IBM that a cache hit rate of 99% and above is
recommended"

I found the following statement in the web interface.

The server database performs best with a cache hit ratio above 97% in the
database bufferpool. To tune the bufferpool size, (a) reset the bufferpool
statistics, (b) execute server operations that use the database, and (c)
view the database details to see if the cache hit ratio is above 97%. If
the cache hit ration is NOT above this percentage, increase the size of the
BUFPOOLSIZE specification in the server options file.

Conflicting advice?  Perhaps your 97.7% is good and no problem exists.
Let's hear from others.  Please......


Ken
khoracek AT incsystem DOT com


>>> Sascha.Braeuning AT SPARKASSEN-INFORMATIK DOT DE 08/21/2002 12:46:04 AM >>>
Hi all,

first I've to thank all participants for the amount of answers I got on my
latest questions. Now I've got a new one which relates on the
bufferpoolsize and the cache hit rate on OS/390 TSM-Servers.

we use the following bufpoolsize:  32768
our chache hit rate:            97,7 %

I know from my training at IBM that a cache hit rate of 99 % and above is
recommended. Is it possible, that a lower cache hit rate can cause
performance-problems? What is your experience?


MfG
Sascha Bräuning


Sparkassen Informatik, Fellbach

OrgEinheit: 6322
Wilhelm-Pfitzer Str. 1
70736 Fellbach

Telefon:   (0711) 5722-2144
Telefax:   (0711) 5722-1630

Mailadr.:  sascha.braeuning AT sparkassen-informatik DOT de