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How to Upgrade domU Kernel

This article introduces the procedure to upgrade domU kernel of Applogic template/class based appliance(PV appliance) from 2.9 to 3.7.

Background

From AL 2.9 to 3.5, Applogic template/class appliances are based on CentOS 5.4 and 5.5. CentOS 5.4/5.5 provide separate kernel packages for HVM and PV mode. The Xen PV capable kernel package name is usually in form of kernel-xen-xxxxx. Since AL 3.7, Applogic template/class appliances are based on CentOS 6.3 which utilizes single kernel package to support both HVM and PV.

Per-upgrade

1. Backup appliance which will upgrade kernel
2. Notes appliance OS release and kernel
3. Verify appliance can access internet

How to upgrade domU kernel from 2.9 to 3.5

1. Ssh to appliance and execute "yum install kernel-xen" to install latest Xen kernel, then documents the new kernel and initrd image name.
2. Exeucte below CLI to verify new initrd image has already included xenblk.ko module or not.

   gunzip < [full path to new intrid image] | cpio -t | grep lib/xenblk.ko  
   

   If initrd image does not include xenblk.ko, add xenblk.ko into initrd image.

   mkinitrd -f --without-usb --with=xenblk [full path to new intrid image] [kernel version]
   

   Here is a sample. Please use your initrd image file name and kernel version in CLI.

   gunzip < /boot/initrd-2.6.18-xenU.img | cpio -t | grep lib/xenblk.ko
   mkinitrd -f --without-usb --with=xenblk /boot/initrd-2.6.18-xenU.img 2.6.18-xenU
   

3. Update /boot/grub/menu.lst to utilize the new kernel and initrd image. After it's done, restart appliance.

How to upgrade domU kernel since 3.7

1. Ssh to appliance and execute "yum install kernel"(use kernel as package name, not kernel-xen) to install latest HVM and PV capable kernel, then documents the new kernel and initrd image name
2. Update /boot/grub/menu.lst to utilize the new kernel and initrd image. After it's done, restart appliance.

Note: This instruction only applies to those Applogic template/class based appliances. It's customer responsibility to choose the stable Linux kernel to upgrade to. Additionally, It's also customer responsibility to make the decision of what is the best approach to upgrade kernel of appliance which is NOT based on AppLogic template/class.