RE: Solaris-Single node Vs Linux 3 nodes RAC

From: Jorgensen, Finn <>
Date: Mon, 5 Nov 2012 18:02:54 -0500
Message-ID: <9CE162BC5ED2C643956B526A7EDE46FF0359430A9621_at_EXM-OMF-04.Ceg.Corp.Net>

Veritas inherently does not do DIO unless you've implemented ODM/Quick IO which is unlikely. That means buffered IO. I've personally seen what a huge difference it can make when the OS has buffered the data already. It's very possible this is the reason for the difference.


-----Original Message-----
From: [] On Behalf Of Frits Hoogland Sent: Monday, November 05, 2012 11:43 AM To:
Cc: oracle-l
Subject: Re: Solaris-Single node Vs Linux 3 nodes RAC

Please use a sql trace at level 8 to understand what oracle is doing in both cases. ASM is inherently DIO thus no buffering. If the database on Solaris does not do DIO, and there is much memory free, there is a chance the OS buffers the IO's

Frits Hoogland
+31 6 53569942 <+31%206%2053569942>

Op 5 nov. 2012 om 16:44 heeft Sudhakar G Pillai <> het volgende geschreven:

I appreciate if you could shed some light on which direction to go. I have Solaris non-rac database running with 26GB SGA ( PDB-NONRAC(Solaris)) and 3 node RAC database in Linux with 100GB SGA ( PDB-RAC ) . One of our program runs 3 times slower on RAC vs Soalris. Same SQL code , same plan, and same oracle version etc. Solaris has file system with Veritas LVM and Linux has ASM. Here is the output of 10046: SQL ID: 9txtqr9tdkcbs

  Event waited on                             Times   Max. Wait  Total
  • Waited ---------- ------------ PDB-NONRAC(Solaris) db file sequential read 413468 0.32 234.99 PDB-RAC(LINUX) db file sequential read 434173 0.50 2138.24

Is it Veritas's LVM caching playing the role here vs no-caching in ASM?

 Thank you,
Sudhakar G Pillai



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Received on Tue Nov 06 2012 - 00:02:54 CET

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