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Re: I/O Performance/bottlenecks on EMC Symmetrix

From: Gaja Krishna Vaidyanatha <>
Date: Fri, 14 Sep 2001 02:50:02 -0700
Message-ID: <>

!! 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 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.

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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 Krishna Vaidyanatha
Director, Storage Management Products,
Quest Software, Inc.
Co-author - Oracle Performance Tuning 101

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Author: Gaja Krishna Vaidyanatha

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Received on Fri Sep 14 2001 - 04:50:02 CDT

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