Monday, 19 August 2013

Kernel Upgrade Interview Questions

1)What is your present patch level?
A: 710

2)From which patch level did you upgrade it?
A: 720

3) Why do you go for kernel patch upgrade?
A: we usually do it when there is a problem with the existing kernel files &
When we go for latest functionality like support packs implementation or add-ons or plug-in implementation.
When sap recommends in early watch alerts we go for the kernel patch upgrade.

4)What are the files do you downloaded from service market place?
A: 1) sapexe file (db independent) & sapexedb file (db dependent)……

5)How many ways do you know the current patch level?
A: At os level -> login with sidadm and use the command disp+work
At sap level -> system -> status.

6)What are the problems do you faced while kernel patch upgrade?
PROBLEM 1:we generally forgot about file permissions
PROBLEM2: we should stop saposcol & listener otherwise it give problems.

7)What are the prerequisites for kernel patch upgrade?
A: we should take the backup of old kernel & check for the existing patch version to download latest version.

8)how do you uncar the downloaded car files?
A: By using command SAPCAR -xvf 

9)Why do you overwrite the old kernel instead of replace?
A: Because latest kernel consist only updated kernel files only so to use the remaining files we use to overwrite the kernel.

10)What are the post requisites for kernel patch upgrade and why?
A: run the scripts for the permissions in non windows environment & check for the kernel patch version whether it is updated or not?

11)What is default kernel location
A: Usually it is located in: </usr/sap/SID/SYS/exe/<uc or nuc>/<system>. it might also be located in /usr/sap/SID/SYS/exe/run 



  1. hi kapil, i have a question, is it ok if we upgrade kernel in one central host ? will it reflect all other application servers if we do it..
    i am new to sap , please comment ..

    1. Yeah. We had /sampnt/SID/exe with soft link to /usr/sap/SID/SYS/exe.. we just update the new kernel here and take a restart. It should reflect in all local exe folders. You can check sapcpe.log in individual instance work folder.

  2. hi kapil, very nice post regarding kernel upgrade,
    recently i have faced one question regarding kernel upgrade, he asked me do you know one option kernel upgrade without stopping sap application?
    i dont know, please let me know.

    1. You can use RKS (Rolling kernel Switch) for kernel upgrade with stopping application.

    2. Could u please explain how exactly it works

  3. which one is better RKS or normal