This article describes how to start a Citrix ADC appliance with different kernel version other than the one installed on the appliance.

Background

Before you can start a Citrix ADC appliance with a different kernel version than the one installed on the appliance, you must know the kernel version installed on the appliance. This is required to ensure that you select the correct version of the kernel that can be installed on the appliance to start the appliance.

To verify the kernel version installed on the appliance, you can use any of the following methods:

• When you start the appliance, the kernel version is displayed immediately after the appliance starts. This information is also stored in the "/flash/boot/loader.conf" file.

• Run the show version command.

• Run the lsmod command.

Instructions

To start a Citrix ADC appliance with a different kernel version than the one installed on the appliance, complete the following procedure:

1. Restart the Citrix ADC appliance.

2. After the kernel starts loading, press Ctrl+C to interrupt the boot up process.

3. To verify the kernel installed on the appliance, run the show command from the ok prompt, as shown in the following screen shot:

   
   
   Note:When you press Ctrl+ C and type Show command you will be in Kernel prompt. Ok is by default present in the prompt.
   Do not type ok for any command. Just type the command mentioned. for example: unload /ns-7.0-57.1 

4. Run the ls command to verify the kernel files available on the appliance, as shown in the following screen shot:

   

5. Run the following command to unload the kernel:
   ok unload /ns-7.0-57.1

6. Run the following command to set the desired kernel:
    set kernel=/ns-8.1-60.3

7. Run the following command to load the kernel with which you want to start the appliance:
   ok load /ns-8.1-60.3

8. To verify that the kernel is loaded, run the show command, as shown in the following screen shot:

   

9. Run the following command to start the appliance with the kernel you have loaded:
   ok boot

10. Log on to the appliance after the boot up process is complete.

11. Run the following command to verify the kernel installed on the appliance:
    show ns version

Note: If you want to use the same kernel, you must complete the upgrade or downgrade process for the Citrix ADC software release. After you restart the appliance, the kernel is installed according to the software release installed on the appliance.