techblog 

Oracle has made a big play in recent years on getting everyone to use Linux for running their database on, probably so you can afford to buy more oracle licenses. However all the oracle documentation I have seen seems geared towards the 2.4 Linux kernel. With the newer 2.6 kernel, available with RHEL 4.0, the treatment of raw devices changes, and the old /etc/sysconfig/rawdevices file is deprecated in favour of udev.

Why raw devices, you may ask? We are investigating Oracle RAC running on Linux x86-64, with ASM for storing the database datafiles, but unfortunately for RAC you need a shared voting disk and OCR files and these can’t go in ASM. This leaves 2 alternatives, OCFS2 or raw devices. OCFS2 is favoured by many, but is NOT YET CERTIFIED by Oracle, so has been discounted by us.

There is so little information out there on using udev, I’ve cobbled together a hybrid rawdevices/udev solution:

Edit /etc/sysconfig/rawdevices

/dev/raw/raw1   /dev/sdc2
/dev/raw/raw2   /dev/sdc3
/dev/raw/raw3   /dev/sdc1

Stop/start rawdevices /etc/init.d/rawdevices

Edit /etc/udev/permissions.d/50-udev.permissions

raw/*:oracle:oinstall:0660

This is crucial in setting the permissions of the devices on a reboot, if these devices are not owned by oracle you will be in a whole world pain. The above approach works quite well over reboots, but if anyone out there can do this without /etc/sysconfig/rawdevices, I’d be interested to hear it. I suspect you put a script into /etc/udev/scripts