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Disk I/O Pacing settings on AIX 5.3 LPARs with vscsi disks

  • 1.  Disk I/O Pacing settings on AIX 5.3 LPARs with vscsi disks

    Posted Thu December 23, 2010 04:04 AM

    Originally posted by: tech100


    P6 system.

    I noticed the minpout/maxpout are set to 0 (default) on my AIX 5.3 LPARs using VSCSI disks (SAN disks served by VIOS 2.2). Knowing that defaults in AIX 6.1 are maxpout=8193 and minpout=4096 and also knowing tunning of this parametters is difficult, please tell me what are your recommendations in such case. Should I leave it as it is now default or adjust it?

    http://publib.boulder.ibm.com/infocenter/aix/v6r1/topic/com.ibm.aix.prftungd/doc/prftungd/disk_io_pacing.htm
    #AIX-Forum


  • 2.  Re: Disk I/O Pacing settings on AIX 5.3 LPARs with vscsi disks

    Posted Mon January 03, 2011 07:52 AM

    Originally posted by: nagger


    I would leave them alone unless you have had AIX Support analyse a perfPMR and found your I/O pattern is very unusual and untypical.

    I have found it is easy to reduce I/O performance by fiddling with these and have fixed a few customer machines by simply returning to the defaults!

    Hope this helps, Nigel Griffiths
    #AIX-Forum


  • 3.  Re: Disk I/O Pacing settings on AIX 5.3 LPARs with vscsi disks

    Posted Tue January 11, 2011 03:09 PM

    Originally posted by: tech100


    what defaults do you mean?

    AIX 5.3 0/0
    AIX 6.1 4096/8192 ?

    minpout/maxpout AIX versions comparison

    Aren't these settings rather hardware perfromance dependent? eg. having now modern/faster disks shouldn't it be tuned now to get new "hardware" benefits?

    I am wonder because if IBM modified defaults for AIX 6.1 so maybe on the same hardware with AIX 5.3 it's defaults should also be tuned??
    #AIX-Forum


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