Re: Async and Direct I/O On Solaris using VXFS

From: Grzegorz Goryszewski <>
Date: Tue, 28 Jun 2011 17:21:56 +0200
Message-ID: <>

On 2011-06-28 17:02, rajesh koppada wrote:
> I was following the below link and tracing the systems calls ,
> We are using oracle version on VXFS file systems on Sun solaris
> 4294/1: open("/users/oracle/undofile/undotbs01.dbf", O_RDWR|O_DSYNC) = 10
> 4294/1: ioctl(257, (('V'<<24)|('X'<<16)|('F'<<8)|1), 0x00000004) = 0
> any idea how to intepert this ioctl arguments ?? Just to ensure we are getting Direct I/O on VXFS file systems.

Looks like a bug, do You have patch *10336129 installed?* :


Poor Oracle IO performance on VXFS for RDBMS 11gR2 compared to 10gR2 on Solaris

This problem is introduced in RDBMS on SolarisRegardless of what you Oracle "filesystemio_options = asynch | none" is set, Oracle issues "ioctl(fd, VX_SETCACHE, VX_DIRECT).".The ioctl effectively disables VXFS caching, and renders considerable IO slow down compared to 10.2.x for IO events like "db file sequential read" and "db file parallel read".


The ioctl can be observed with truss:

|21770/1: 17.5346 0.0059 ioctl(259, (('V'<<24)|('X'<<16)|('F'<<8)|1), 0x00000004) = 0|


This problem only impacts regular buffered IO on VXFS.

VXFS filesystems using ODM or mount option "mincache=direct" is not impacted.

RAC Clustered filesystems are not impacted because ODM is a requirement.


Apply Oracle patch# 10336129 to RDBMS



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Received on Tue Jun 28 2011 - 10:21:56 CDT

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