Re: How much RAM is to much

  • From: Gaja Krishna Vaidyanatha <gajav@xxxxxxxxx>
  • To: D'Hooge Freek <Freek.DHooge@xxxxxxxxx>
  • Date: Fri, 11 Feb 2011 13:46:55 -0800 (PST)

Hi Freek,

What you said is true for filesystems that do NOT allow "direct I/O" mount 
options in their respective mount commands. But for those filesystems that do 
(i.e. vxfs, jfs etc) support the relevant direct I/O mount options, the direct 
I/O mount option has always (in my experience) been required in addition to 
setting filesystemio_options to SETALL. Setting just the filesystemio_options 
the init.ora (in those cases) did not create the desired result. 

If you have observed the "lack of the mount option" in recent times on those 
filesystems where direct I/O mount options ARE supported (i.e. vxfs, jfs etc), 
please advise. There is always something to learn new each day :)


 Gaja Krishna Vaidyanatha,
Founder/Principal, DBPerfMan LLC
Phone - 001-(650)-743-6060
Co-author:Oracle Insights:Tales of the Oak Table -
Co-author:Oracle Performance Tuning 101 -

From: D'Hooge Freek <Freek.DHooge@xxxxxxxxx>
To: "ChrisDavid.Taylor@xxxxxxxxxxxxxxx" <ChrisDavid.Taylor@xxxxxxxxxxxxxxx>; 
"andrew.kerber@xxxxxxxxx" <andrew.kerber@xxxxxxxxx>; Gaja Krishna Vaidyanatha 
Cc: "RStorey@xxxxxxxxxxxxxxxxxx" <RStorey@xxxxxxxxxxxxxxxxxx>; 
oracle-l-freelists <oracle-l@xxxxxxxxxxxxx>
Sent: Thu, February 10, 2011 11:38:43 PM
Subject: RE: How much RAM is to much

Hmm, I don't think you need to mount with directio when setting the 
filesytemio_options parameter to "directIO" or to "setall".
When using rac with nfs, the oracle required mount options do not include a 
setting to force directIO (but on solaris they do).
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Mount Options for Oracle files when used with NAS devices [ID 359515.1]


Freek D'Hooge
Oracle Database Administrator
email: freek.dhooge@xxxxxxxxx
tel +32(0)3 451 23 82
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Taylor, Chris David
Sent: donderdag 10 februari 2011 20:58
To: 'andrew.kerber@xxxxxxxxx'; 'Gaja Krishna Vaidyanatha'
Cc: 'RStorey@xxxxxxxxxxxxxxxxxx'; 'oracle-l-freelists'
Subject: RE: How much RAM is to much

Doesn't direct IO have to configured in the mount options for the filesystems?  
(Not just specified in the Oracle parameters)
Otherwise, you're in fact not using it, right?

Or do filesystems now-a-days get mounted with direct as an option automatically 
in Linux?

Chris Taylor
Sr. Oracle DBA
Ingram Barge Company
Nashville, TN 37205
Office: 615-517-3355
Cell: 615-663-1673
Email: chris.taylor@xxxxxxxxxxxxxxx
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