Kernel upgrade for Linux(OEL/RHEL) using up2date

Given procedure helpful to upgrade the Linux(OEL/RHEL) kernel using up2date command

Required Backups:

1.      Ensure full system backup

2.      Take the backup of the /etc/grub.conf file.

    #cp /etc/grub.conf /etc/grub.conf.bak

Procedure to upgrade kernel:

1. register the system to the ULN(Unbreakable Linux Network) with you Linux support CSI

     #Up2date –register

2.      Go to linux.oracle.com and subscribe the server to the RHEL/OEL 5.x/6.x patch channel which ever is required

Eg:

- go to the "Systems" tab and click on your server
- Click on "Manage Supscriptions" and select "Enteprise Linux 5 Update 4 Patch ( ARCH, eg: i386 )" and "Enteprise Linux 5 Update 4 installation media copy ( ARCH )", remove "Enterprise Linux 5 Latest ( ARCH )"
- click on "Save Subscriptions"

3.      Get the kernel package; you can download the kernel package from Oracle ULN

1. First find what and all kernel modules available for Upgrade

[root@myserver ~]# up2date --list |grep -i kernel

kernel-headers           2.6.18         194.17.1.0.1.el5  i386 

kernel                   2.6.18         194.17.1.0.1.el5Pkg name/pattern

kernel-devel             2.6.18         194.17.1.0.1.el5Pkg name/pattern

b.     get the required packages

[root@myserver ~]# up2date --get kernel kernel-devel kernel-headers

...

Fetching package list for channel: el4_i386_latest...

########################################

kernel-2.6.9-89.0.0.0.1.EL.i686.rpm...

########################################

kernel-devel-2.6.9-89.0.0.0.1.EL.i686.rpm...

########################################

   

The packages will download into /var/spool/up2date

#ls -l /var/spool/up2date/kernel-*rpm

Note: If you want to migrate to new version upgrade the other packages also using up2date

And reboot the server

4. Install kernel package

.
Note: Never use "rpm -Uvh" to "update" the kernel.  Use rpm –ivh only to install Kernel package and can boot with the new kernel.  You can easily boot with old kernel if anything goes wrong.

# rpm -ivh kernel-<version>.rpm

Alternatively you can use up2date directly to upgrade

a.       Run the "up2date -fu kernel", and it will upgrade your kernel(Kernel upgrade only)

For Migration to new version of Linux need to upgrade packages also.

b.      "up2date -fu", will upgrade your kernel and all of your installed packages

5. Check /boot/grub/grub.conf.

A new kernel section is found to append to this file after you install the new kernel.

Find the "default" field; make sure it points to the right kernel you want to bootup. you can modify the "default" value, just remember this value is counted from "0" which means the "0" is the first kernel, the "1" is the second kernel.

6. If your old system has installed some third party drivers, these drivers will not go into the new kernel, you need reinstall all the third party drivers.

7. Normally, only the new kernel package is needed, but sometimes the new kernel will need to install or upgrade other packages first (dependency problem), such as kernel-devel, ecryptfs-utils, mkinitrd, etc.  If you use yum to update, yum will resolve these dependencies for you.  If you use the rpm command, it will error out but tell you which dependencies it requires.

8. If your old system has installed kernel-devel package and if you want to keep the kernel-devel package consistent with the new kernel, you can update the kernel-devel, just remember that after you update it, it will not be very easy to go back to the old version, and some of your developing application will be affected.

Back-Out Plan:

1.      Reboot the system in to single user mode.

2.      edit /etc/grub.conf and change the “default” value to the old kernel.