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Home -> Community -> Mailing Lists -> Oracle-L -> Re: I/O Performance/bottlenecks on EMC Symmetrix
!! Please do not post Off Topic to this List !!
Gaja,
I REALLY like #14 :)
Rachel
>From: Gaja Krishna Vaidyanatha <oraperfman_at_yahoo.com>
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: Re: I/O Performance/bottlenecks on EMC Symmetrix
>Date: Fri, 14 Sep 2001 02:25:24 -0800
>
>!! Please do not post Off Topic to this List !!
>
>Hi Don,
>
>I think I can get your "don't believe everything you
>hear list" to 10....no make that 14. This is not
>specific to any storage vendor :
>
>8) I/O access patterns on datafiles and redo logfiles
>are the same, hence can co-exist without any I/O
>issues.
>
>9) A logical device with 16 drives will perform
>exactly like 4 logical devices with 4 drives each. So
>always create one huge logical volume with all of your
>drives.
>
>10) Even if you use Parallel Query and Database
>Partitioning, you can still put everything on the same
>large logical device. Don't worry about "localized I/O
>isolation" it is not relevant.
>
>11) Don't worry about "availability issues" with the
>one huge logical volume, even though you will affect
>every database component with the failure of 1 disk
>drive. That's because everything is mirrored.
>
>12) We have benchmarked this new I/O methodology on a
>system with 1440 drives. We did another benchmark with
>2400 drives and it worked really well.
>
>13) I/O diagnostics can be done only at the
>file-level, as object-level I/O diagnostics is
>extremely difficult if not impossible. Thus, create
>one huge logical volume and put all of your database
>components on the same logical devices to eliminate
>hotspots.
>
>14) We are XXX Corporation, the gods of disks, and we
>have invented an "7th fibonacci series inverse
>convoluted extremely complex heat and pressure
>sensitive algorithm", that will measure the angle of
>the sun rays coming through the window in your
>datacenter and take into consideration the time & date
>of the day, determine the gravitational pull of the
>moon, to manage the cache in our storage array which
>will eliminate all I/O bottlenecks and cure cancer
>automatically 7x24xforever.
>
>Don't we love our jobs!!!!
>
>Gaja
>
>--- Don Granaman <granaman_at_home.com> wrote:
> > !! 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!]
> >
> > ----- Original Message -----
> > To: "Multiple recipients of list ORACLE-L"
> > <ORACLE-L_at_fatcity.com>
> > Sent: Thursday, September 13, 2001 6:55 AM
> >
> >
> > !! 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
> >
> > =======================================================
>
>=====
>Gaja Krishna Vaidyanatha
>Director, Storage Management Products,
>Quest Software, Inc.
>Co-author - Oracle Performance Tuning 101
>http://www.osborne.com/database_erp/0072131454/0072131454.shtml
>
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>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>--
>Author: Gaja Krishna Vaidyanatha
> INET: oraperfman_at_yahoo.com
>
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Rachel Carmichael INET: carmichr_at_hotmail.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).Received on Fri Sep 14 2001 - 11:26:57 CDT
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