If you're in RHEL4, you just point your voting, OCR, etc. at the relevant /dev/mapper/mpath0, etc. device, and Oracle uses the O_DIRECT flag when it opens the device. What is the error you're getting?

Matt

--
Matthew Zito
Chief Scientist
GridApp Systems
P: 646-452-4090
mzito@gridapp.com
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From: owner-toasters@mathworks.com on behalf of Alexander Schalek
Sent: Mon 11/5/2007 10:02 AM
To: toasters@mathworks.com
Subject: accessing lun as a raw device using dm-multipathing from a rhel host

Hi!

I have some troubles with a oracle rac installation on netapp fcp luns.

We use rhel4 u5 with dm-multipathing with a 2.6 kernel

Currently we have 4 partitioned and multipathed luns maped to the hosts(mpath0-3) but the rac installation exits with an error.

I found the following lines in the fcp host utilities setup guide:

Accessing LUNs using dm-multipath

Accessing LUNs as a raw devices

Overview

Instead of creating a file system, you can access a LUN as a raw device.

Be sure to use the /dev/mapper/ device created by dm-multipath to access the raw

device.

For the Linux 2.6 kernel used by RHEL 4, do not use the raw interface. Instead

open the device using the open call with the O_DIRECT flag.

*****

So I have to access the devices using the open call with the O_DIRECT flag!?

Can anyone of you guys explain this sentence to me?

How do I do that?

Many thanks and best regards,

Alexander