How to Upgrade RHEL Server

Before Performing the OS upgrade we have to take the OS BACKUP so below are the tool which are more effective in production environment.

For Physical server we can take backup through mondo or we can take dump tool for the server.

Mondo is a open source tool for complete back of OS Apart from other file system .

mondo will create a iso of the current OS in running environment without down time.

Dump is the most effective tool for the restore of OS But it take too much time.

How to Upgrade RHEL 6.1 to 6.3

Update YUM repo configuration:
                sudo yum clean all
                cd /etc/yum.repos.d
                sudo vi test.repo

[rhel6.3]
name=Local RHEL 6.3 repo
baseurl=file:///rhel6
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-beta,file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release

[rhel6.3 patches]
name=Local RHEL 6.3 repo
baseurl=file:///rhel/pkg
gpgcheck=1
enabled=1

If you want to exclude some pkg not to update then

vi /etc/yum.conf
add exclude
exclude=mysql



                Updated yum first:
                sudo yum update yum

            Updated all packages w/dependencies:
                sudo yum update

            Verified the kernel installed
                rpm -qa | grep kernel

     
In rhel 5.4 to 5.8 we disabled these services  but now in rhel6.3 this is not present

sudo /sbin/chkconfig --list |grep -i kudzu
sudo /sbin/chkconfig --list |grep -i iscsi
sudo /sbin/chkconfig --list |grep -i iscsid
sudo /sbin/chkconfig --list |grep -i firstboot
sudo /sbin/chkconfig --list |grep -i yum-updatesd
sudo /sbin/chkconfig --list |grep -i setroubleshoot
sudo /sbin/chkconfig --list |grep -i mcstrans


            Disabled unneeded services per current build standard:
                sudo /sbin/chkconfig kudzu off
                sudo /sbin/chkconfig iscsi off
                sudo /sbin/chkconfig iscsid off
                sudo /sbin/chkconfig firstboot off
                sudo /sbin/chkconfig yum-updatesd off
                sudo /sbin/chkconfig setroubleshoot off
                sudo /sbin/chkconfig mcstrans off

            Enabled kdump:check wheather the crashkernel=auto or not
                sudo vi /etc/kdump.conf

#added the following lines - make sure to change path to include correct hostname

###crashed kernel dump######NFS Server Ip where this crash log stores######
net 192.168.1.100:/server/storage
path /dkserver
core_collector makedumpfile -c --message-level 1 -d 31

                sudo /sbin/chkconfig kdump on

                Reboot the server, verify kernel and kdump:
                sudo /sbin/reboot
                uname -r
             
cat /etc/redhat-release
                /sbin/service kdump status


If u have the virtual machine then this required for the kernel & intird work perfectly

            Re-run VMWare Tools config to rebuild initrd against new kernel:
                sudo /usr/bin/vmware-config-tools.pl --default

            Reboot off new initrd:
                sudo /sbin/reboot