CentOS - How to Upgrade Xen + Xen Kernel and what to do If fail to boot?
Tips: Keep one Linux Kernel and one Xen Kernel so If your Xen Kernel failed to boot then you can fix Xen Kernel by rebooting your server with linux kernel.
Login to your SSH Account and run this command:
(Note: Sometimes I use this command "yum upgrade xen", "yum upgrade kernel-xen"
If upgrade is available then you will see "xen" and "xen-kernel" in update list then press "y" and after successfully upgrade type this command
and change boot menu to your latest Xen line.
What to do If you upgrade Xen but in grub.conf show old Kernel Version?
Run this command
yum remove xen*
And remove Xen + Xen Kernel then run this command
yum install xen
If show latest xen + xen kernel then press "y" and wait until installation finish then again go to /etc/grub.conf and update your boot selection to your latest kernel line and then reboot your server.
How to check kernel version?
After upgrading xen, my server can't start and show "kernel panic error"?
Don't worry, reboot your server, press any key when show "CentOS" and select other working kernel then boot with working kernel and again remove "Xen + Xen Kernel" and re-install Xen+Xen-Kernel
There is many list in grub.conf, what I can do?
Remote all other old version of Linux kernel and Xen kernel and keep only 1 linux and 1 xen kernel.