Re: access IO by M/M/m Module

From: Remigiusz Sokolowski <remigiusz.sokolowski_at_nordea.com>
Date: Tue, 27 Sep 2011 07:54:49 +0200
Message-ID: <4E816529.5060802_at_nordea.com>

I may advice You to find "Forecasting Oracle Performance" by Shallahamer. In Cary Millsap's book IIRC there is mainly description of CPU modelling. AFAIK main difference between IO and CPU is that CPU is (number of systems)*M/M/(no of CPUs) while IO is (number of IO drives)*M/M/1, so there are differences between modelling the CPU and IO. Anyway try to get this book

Regrads
Remigiusz

W dniu 27.09.2011 05:17, Sidney Chen pisze:
> Hi,
> When reading the Topic of M/M/m Module in the book <<Optimizing Oracle
> Performance>> by Gary Millsap, I have the idea to verify if our I/O
> subsystem can fit the M/M/m module.
>
> The db is IO intense, 80% db time is spent on "db file sequential read",
> and the avg wait time is 15ms.
> 1. to do the assessment, I extract 3357 lines in one 10046 trace file
> 2. compute the ela time as second(divide by 1000000, keep the distribution
> compact)
> 3. using the mdist.pl to tell if the elapse time for "db file sequential
> read" fit the "exponential distribution".
>
> the result is reject, so i wonder if there are accurate methods to assess.
> Any advise is appreciated.
>
> oracle: ~/scripts$ perl mdist.pl 2.lst
> Hypothesis: Data are exponentially distributed with mean 0.0155063946976467
> Test result: n=2 V=1143.25 p=1.000
> Verdict: *Reject*
>
>
>
>
> --original record in 10046 trace file
> WAIT #19: nam='db file sequential read' ela= 26431 file#=207 block#=258517
> blocks=1 obj#=206447 tim=1284706983664908
> WAIT #19: nam='db file sequential read' ela= 11191 file#=108 block#=1351954
> blocks=1 obj#=206444 tim=1284706983677002
> WAIT #19: nam='db file sequential read' ela= 11836 file#=25 block#=294842
> blocks=1 obj#=206444 tim=1284706983689523
> WAIT #19: nam='db file sequential read' ela= 6268 file#=25 block#=472857
> blocks=1 obj#=206444 tim=1284706983696181
> WAIT #19: nam='db file sequential read' ela= 6339 file#=108 block#=1348802
> blocks=1 obj#=206444 tim=1284706983702664
> WAIT #19: nam='db file sequential read' ela= 7363 file#=25 block#=434781
> blocks=1 obj#=206444 tim=1284706983710368
> WAIT #19: nam='db file sequential read' ela= 12006 file#=176 block#=489651
> blocks=1 obj#=206444 tim=1284706983722477
> WAIT #19: nam='db file sequential read' ela= 18163 file#=107 block#=1728592
> blocks=1 obj#=206444 tim=1284706983740767
> WAIT #19: nam='db file sequential read' ela= 24003 file#=107 block#=1740869
> blocks=1 obj#=206444 tim=1284706983765194
> WAIT #19: nam='db file sequential read' ela= 4780 file#=25 block#=473096
> blocks=1 obj#=206444 tim=1284706983770782
> WAIT #19: nam='db file sequential read' ela= 6644 file#=25 block#=431224
> blocks=1 obj#=206444 tim=1284706983777508
> WAIT #19: nam='db file sequential read' ela= 20201 file#=107 block#=1747395
> blocks=1 obj#=206444 tim=1284706983797791
> WAIT #5: nam='db file sequential read' ela= 89939 file#=207 block#=359305
> blocks=1 obj#=206447 tim=1284706984136333
> WAIT #5: nam='db file sequential read' ela= 21708 file#=25 block#=292852
> blocks=1 obj#=206444 tim=1284706984158777
>
> --record in 2.lst, ela divided by 1000000
> .026431
> .011191
> .011836
> .006268
> .006339
> .007363
> .012006
> .018163
> .024003
> .00478
> .006644
> .020201
> .089939
> .021708
>

-- 
Pole nakazi

----------------------------------------------------------------------
Remigiusz Sokolowski <remigiusz.sokolowski_at_nordea.com>
pos   : DBA at DIiUSI
addr  : Nordea Bank Polska SA, Luzycka 6A Street, 81-537 Gdynia, Poland
phone : +48 58 667 17 43
mobile: +48 602 42 42 77
Nordea Bank Polska S.A. z siedziba w Gdyni, ul. Kielecka 2, 81-303 Gdynia, 
wpisana do Rejestru Przedsiebiorców Krajowego Rejestru Sadowego pod numerem: 0000021828, 
dla której dokumentacje przechowuje Sad Rejonowy Gdansk - Pólnoc w Gdansku, 
VIII Wydzial Gospodarczy Krajowego Rejestru Sadowego, 
o kapitale zakladowym i wplaconym w wysokosci: 277.493.500,00 zlotych, 
NIP: 586-000-78-20, REGON: 190024711--
http://www.freelists.org/webpage/oracle-l

Received on Tue Sep 27 2011 - 00:54:49 CDT