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how to bypass Disk IO buffer in RHEL 5 for oracle

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Md. Minhaz Khan
Super Advisor

how to bypass Disk IO buffer in RHEL 5 for oracle

Dear All,

In HP-UX, we have bypass our OS cache for oracle by using "mincache=direct,convosync=direct" in the /etc/fstab file which is attached with this thread.

My query is how to do this in RHEL 5.4 64 bit OS??

Thanks
Minhaz

2 REPLIES
Matti_Kurkela
Honored Contributor
Solution

Re: how to bypass Disk IO buffer in RHEL 5 for oracle

In Linux, this can be done within Oracle: there is no need to do anything at the OS level.

In Oracle 9i or 10g, set Oracle parameter "filesystemio_options" to "setall" or "directio", and Oracle will automatically use Linux API to request direct I/O whenever appropriate.

(With setting "setall", you'll also get asynchronous I/O whenever appropriate; with "directio" you'll get Direct I/O only.)

This document is written for RHEL 4 and older, but is mostly good for RHEL 5 too:

http://www.puschitz.com/TuningLinuxForOracle.shtml#EnablingAsynchronousIOSupport

Here's a RedHat document for configuring Oracle on RHEL 5. It's talking about GFS, but the asynchronous and direct I/O features will work on ext3 filesystems too.

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Configuration_Example_-_Oracle_HA_on_Cluster_Suite/oracle_settings.html

MK
MK
Md. Minhaz Khan
Super Advisor

Re: how to bypass Disk IO buffer in RHEL 5 for oracle

Thanks a lot MK. I have got my answer.

BR
Minhaz