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Message Posted: Wed, 20 Jun 2013 @ 01:12:41 GMT


     
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Subj:   Re: High AMP I/O Skew Always
 
From:   Clark, Dave

You will probably have to open up an incident with the GSC to pursue this but here are a few queries to get you going. You will need to run the queries while the problem is seen. If there is no evidence of skew here, you can use the ResUsage data (sldv) to pursue historic issues with IO skew.

-dave.clark

Check for skew associated with a session:
-----------------------------------------

     SEL UserName (TITLE 'Users', format 'X(20)'),
     SessionNo (TITLE 'Session', FORMAT 'Z(9)ZZZ'),
      (100 * (1 - (AvgAmpIOCnt / NULLIFZERO(HotAmp1IO))))        (TITLE 'Amp IO
     Skew %',FORMAT 'ZZ9')
     FROM TABLE (SYSLIB.MonitorSession(-1,'*',0)) AS t1
     WHERE AmpState='ACTIVE' AND HotAmp1IO > 0
     ORDER BY 1,2;

Check for node disk skew:
-------------------------

     SEL  CAST((HighDiskProcId/32)*100 AS INTEGER) + (HighDiskProcId MOD 32)
             (TITLE 'High Disk//Use Node', FORMAT 'ZZ9-99'),
          HighDisk (TITLE 'High Disk//% Use', FORMAT 'ZZ9.99'),
          AvgDisk (TITLE 'Average Disk//% Use', FORMAT 'ZZ9.99'),
          (100 * (1 - (AvgDisk / NULLIFZERO(HighDisk))))
             (TITLE 'Node Disk//Skew(% Use)',FORMAT 'ZZ9.99'),
          CAST((HighDiskIOProcId/32)*100 AS INTEGER) + (HighDiskIOProcId MOD 32)
             (TITLE 'High Disk//IO Node', FORMAT 'ZZ9-99'),
          HighDiskIO (TITLE 'High Disk IO', FORMAT 'ZZZ,ZZZ,ZZ9'),
          AvgDiskIO (TITLE 'Average Disk IO', FORMAT 'ZZZ,ZZZ,ZZ9'),
          (100 * (1 - (AvgDiskIO / NULLIFZERO(HighDiskIO))))
            (TITLE 'Node Disk//Skew (# IO)',FORMAT 'ZZ9.99')
     FROM TABLE (SYSLIB.MonitorPhysicalSummary()) AS t1;

Check for Virtual Amp Disk Use Skew:
------------------------------------

     SEL  CAST((HiDiskAmpProc/32)*100 AS INTEGER) + (HiDISKAmpProc MOD 32)
               (TITLE 'High Disk//Node', FORMAT 'ZZ9-99'),
          HiDiskAmpNo (TITLE 'High Disk//Use Amp', FORMAT 'ZZZZZ9'),
          HiDiskAmp (TITLE 'High Disk Use %', FORMAT 'ZZZ,ZZZ,ZZ9.99'),
          AmpAvgDisk (TITLE 'Average Disk Use %', FORMAT 'ZZZ,ZZZ,ZZ9.99'),
          (100 * (1 - (AmpAvgDisk / NULLIFZERO(HiDiskAmp))))
             (TITLE 'Virtual Disk//Use Skew %',FORMAT 'ZZ9')
     FROM TABLE (SYSLIB.MonitorVirtualSummary()) AS t1
     WHERE HiDiskAmp > 0;

Check for Virtual Amp Disk Io Skew:
-----------------------------------

     SEL CAST((HiDiskAmpIoProc/32)*100 AS INTEGER) + (HiDiskAmpIoProc MOD 32)
              (TITLE 'High Disk//IO Node', FORMAT 'ZZ9-99'),
         HiDiskAmpIONo (TITLE 'High Disk//IO Amp', FORMAT 'ZZZZZ9'),
         HiDiskAmpIO (TITLE 'High Disk IO', FORMAT 'ZZZ,ZZZ,ZZ9'),
         AmpAvgDiskIO (TITLE 'Average Disk IO', FORMAT 'ZZZ,ZZZ,ZZ9'),
         (100 * (1 - (AmpAvgDiskIo / NULLIFZERO(HiDiskAmpIo))))
             (TITLE 'Virtual Amp//Disk IO Skew %',FORMAT 'ZZ9')
     FROM TABLE (SYSLIB.MonitorVirtualSummary()) AS t1
     WHERE HiDiskAmpIo > 0;


     
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