Thursday, 20 December 2012

Installing Oracle Unbreakable Enterprise Kernel (UEK) on CentOS / RHEL

This page describes the process of how to install Oracle's Unbreakable Enterprise Kernel (UEK or kernel-uek) on Centos or RHEL.

Why use UEK?

Why would you want to install the Oracle UEK on CentOS or RHEL?  If you're planning to run Oracle RAC on CentOS/RHEL 6.3 virtual machine (under RHEV/oVirt), you're gonna need it!*  Since RHEL v6.1 Oracle are no longer providing oracleasm drivers for the newer kernels.  They have instead decided to bundle the oracleasm drivers into their Unbreakable Enterprise Kernel.  This actually makes installing Oracle RAC a little easier as you don't have to go searching for the oracleasm driver specific to your kernel!  Just do a yum install! Yes, even on CentOS or RHEL!

Where to get Kernel-UEK from

Oracle have made their UEK available through their public YUM repository (  It is freely available and is the best place to get it and to keep it updated easily.
Download the Oracle yum repo file on to your machine:
sudo mv public-yum-ol6.repo /etc/yum.repo.d/public-yum-ol6.repo

Modify Oracle's repo file

Edit the newly downloaded repo file to disable all repos EXCEPT the ol6_UEK_latest repo, by setting the following under each repo section:
If your system is behind a proxy, add a proxy entry under the [ol6_UEL_latest repo] heading, as follows:
Your system should now have access to the new repo.  You can run yum check-update to make sure there are no connectivity issues to the configured repos.

Installing kernel-uek

To install the new UEK kernel, simply run the following command:
sudo yum install -y kernel-uek kernel-uek-devel kernel-uek-doc kernel-uek-firmware
This will not override the default kernel boot option, so this would be a good time to reboot your system and select the UEK kernel from the grub menu to make sure it runs ok.
Once you are happy the system boots properly, you can set the UEK kernel as the default in the usual manner (beyond the scope of this page).

*You could do away with asmlib entirely, if your devices are detected properly as SCSI devices. Just use udev instead.

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