Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Re: I/O Performance/bottlenecks on EMC Symmetrix

Re: I/O Performance/bottlenecks on EMC Symmetrix

From: <nlzanen1_at_EY.NL>
Date: Thu, 13 Sep 2001 08:20:19 -0700
Message-ID: <F001.0038D2F6.20010913071527@fatcity.com> 






!! Please do not post Off Topic to this List !!




Hi,



The other workload I would say was about the same (Relatively speaking)
Both machines did have idle time on the CPU (I/O intensive job).
The quicker test machine was a bit stretched on memory at the time (running
about 8 databases) but not too bad.



The only thing I can think of is pi** poor performance (3 p's you don't
want in marketing) of the symmetrix disks.



One point this symmetrix is loaded with 36 Gb disks and all of them are
sliced to pieces and than allocated to filesystems. In theory you can be
sharing disks with other high I/O apps (E-mail system etc..).
I do not however have any insight in what is where physically.




Jack






"Don Granaman" <granaman_at_home.com>@fatcity.com on 13-09-2001 16:15:25



Please respond to ORACLE-L_at_fatcity.com



Sent by:  root_at_fatcity.com




To:   Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
cc:    (bcc: Jack van Zanen/nlzanen1/External/MEY/NL)



!! Please do not post Off Topic to this List !!



WOW!  Is the "other" workload on these similar when this job runs?  Are you
sure


the problem is the Symmetrix and not something in the OS or instance
configuration? Does this job spend a lot of time waiting (in Oracle) on
physical


I/O - or on something else?  (I guess if you don't have access to the
machine,


you can't find out though.  The ultimate tuning challenge!)



If the problem is actually Symmetrix I/O, I could only hazard a guess that
it


might be due to RAID-5 for something inappropriate (hot redo log files?) or
extreme I/O contention in the layout.



As far as pointers, pitfalls, and suggestions...  I really have only one:
don't


believe everything you hear!



For example: (top 10 list)


1) "With EMC, RAID-5 won't matter."  (it likely still will - for
write-intensive


stuff)


2) "With EMC, you don't want to stripe." (you might - it can still make a
big


difference)


3) "With the cache, I/O won't ever be a bottleneck."  (until cache becomes
saturated or ...)


4) [Corollary to #3] "Throw out all that basic I/O tuning stuff you
learned"


(but back it up to tape first!)


5) "The best layout is always SAME  - stripe and mirror everything across
everything."


6) "The check is in the mail."


7) "This won't hurt a bit."


[ORA-00051]


Drat!  I crashed before getting to ten!  Sorry, I was up all night
repairing a


bridge...



For more serious and less evasive answers, see Gaja's paper at
http://www.quest.com/whitepapers/Raid1.pdf



-Don Granaman



[OraSaurus - Honk if you remember UFI!]






!! Please do not post Off Topic to this List !!



Hi All,




Does anybody here on the list have experience with EMC/symmetrix storage
units.?



We have our databases on this machine and I have a feeling the the I/O
performance is not very good. I can not proof it since I do not have any
experience/data/access to that machine. We do however have a very
cooperative UNIX group but they also lack experience with performance on
this machine.



Who can give me pointers about I/O throughput that can be reached,
configuration pittfalls etc..



Example:


RS6000 8CPU's and 4Gb memory with storage on EMC/symmetrix. Job takes about
2 hours to complete.



F50 1 CPU 1Gb memory (TEST machine) local disks. same job takes 0.5 hours
to complete.




Jack





De informatie verzonden in dit e-mailbericht is vertrouwelijk en is
uitsluitend bestemd voor de geadresseerde. Openbaarmaking,
vermenigvuldiging, verspreiding en/of verstrekking van deze informatie aan
derden is, behoudens voorafgaande schriftelijke toestemming van Ernst &
Young, niet toegestaan. Ernst & Young staat niet in voor de juiste en
volledige overbrenging van de inhoud van een verzonden e-mailbericht, noch
voor tijdige ontvangst daarvan. Ernst & Young kan niet garanderen dat een
verzonden e-mailbericht vrij is van virussen, noch dat e-mailberichten
worden overgebracht zonder inbreuk of tussenkomst van onbevoegde derden.



Indien bovenstaand e-mailbericht niet aan u is gericht, verzoeken wij u
vriendelijk doch dringend het e-mailbericht te retourneren aan de verzender
en het origineel en eventuele kopieën te verwijderen en te vernietigen.



Ernst & Young hanteert bij de uitoefening van haar werkzaamheden algemene
voorwaarden, waarin een beperking van aansprakelijkheid is opgenomen. De
algemene voorwaarden worden u op verzoek kosteloos toegezonden.




The information contained in this communication is confidential and is
intended solely for the use of the individual or entity to whom it is
addressed. You should not copy, disclose or distribute this communication
without the authority of Ernst & Young. Ernst & Young is neither liable for
the proper and complete transmission of the information contained in this
communication nor for any delay in its receipt. Ernst & Young does not
guarantee that the integrity of this communication has been maintained nor
that the communication is free of viruses, interceptions or interference.



If you are not the intended recipient of this communication please return
the communication to the sender and delete and destroy all copies.



In carrying out its engagements, Ernst & Young applies general terms and
conditions, which contain a clause that limits its liability. A copy of
these terms and conditions is available on request free of charge.









--



Please see the official ORACLE-L FAQ: http://www.orafaq.com


--



Author:


  INET: nlzanen1_at_EY.NL


Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists


--------------------------------------------------------------------

To REMOVE yourself from this mailing list, send an E-Mail message


to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).




--



Please see the official ORACLE-L FAQ: http://www.orafaq.com


--



Author: Don Granaman


  INET: granaman_at_home.com


Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists


--------------------------------------------------------------------

To REMOVE yourself from this mailing list, send an E-Mail message


to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).








De informatie verzonden in dit e-mailbericht is vertrouwelijk en is
uitsluitend bestemd voor de geadresseerde. Openbaarmaking,
vermenigvuldiging, verspreiding en/of verstrekking van deze informatie aan
derden is, behoudens voorafgaande schriftelijke toestemming van Ernst &
Young, niet toegestaan. Ernst & Young staat niet in voor de juiste en
volledige overbrenging van de inhoud van een verzonden e-mailbericht, noch
voor tijdige ontvangst daarvan. Ernst & Young kan niet garanderen dat een
verzonden e-mailbericht vrij is van virussen, noch dat e-mailberichten
worden overgebracht zonder inbreuk of tussenkomst van onbevoegde derden.



Indien bovenstaand e-mailbericht niet aan u is gericht, verzoeken wij u
vriendelijk doch dringend het e-mailbericht te retourneren aan de verzender
en het origineel en eventuele kopieën te verwijderen en te vernietigen.



Ernst & Young hanteert bij de uitoefening van haar werkzaamheden algemene
voorwaarden, waarin een beperking van aansprakelijkheid is opgenomen. De
algemene voorwaarden worden u op verzoek kosteloos toegezonden.




The information contained in this communication is confidential and is
intended solely for the use of the individual or entity to whom it is
addressed. You should not copy, disclose or distribute this communication
without the authority of Ernst & Young. Ernst & Young is neither liable for
the proper and complete transmission of the information contained in this
communication nor for any delay in its receipt. Ernst & Young does not
guarantee that the integrity of this communication has been maintained nor
that the communication is free of viruses, interceptions or interference.



If you are not the intended recipient of this communication please return
the communication to the sender and delete and destroy all copies.



In carrying out its engagements, Ernst & Young applies general terms and
conditions, which contain a clause that limits its liability. A copy of
these terms and conditions is available on request free of charge.









--



Please see the official ORACLE-L FAQ: http://www.orafaq.com


--



Author:


  INET: nlzanen1_at_EY.NL


Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists


--------------------------------------------------------------------

To REMOVE yourself from this mailing list, send an E-Mail message


to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).
Received on Thu Sep 13 2001 - 10:20:19 CDT












Original text of this message













  HOME |
  ASK QUESTION |
  ADD INFO |
  SEARCH |
  E-MAIL US