Kernel Upgrade for SAP Systems...!!!

 This blog explains the procedure to upgrade the kernel for SAP systems

Kernel: Kernel can be defined as a set of executable to run the SAP system.

The procedure to upgrade the kernel is as follows:

1. First of all we need to make sure that the desired SAP kernel version is
compatible with the existing OS Kernel version and SAP product versions with
the help of product availability matrix (PAM).

2. After deciding the target kernel version, download the DB independent, DB
dependent files (SAPEXE_***.***.SAR and SAPEXEDB_***.***.SAR) and place
them in the server.

3. Create a directory in the server with the below command.
mkdir newkernel

4. Copy the DB dependent and DB independent files into the newly created
directory.

cp –pr SAPEXE_***.***.SAR SAPEXEDB_***.***.SAR /newkernel

5. Extract the files using SAPCAR executable. (It can be downloaded explicitly or
the existing one on the server can be used).

./SAPCAR.EXE –xvf SAPEXE_***.***.SAR
./SAPCAR.EXE –xvf SAPEXEDB_***.***.SAR

6. Once the files are extracted assign the suitable authorization and permissions for
the executable.

chown –R <sid>adm:sapsys *
chmod –R 755 *

7. Now stop the application services and make sure that there are no processes
running with <sid>adm user.

8. Take a consistent backup from the global directory. (Make sure to take the
backup from the global directory as the backups taken in the local directories
would be overwritten by the kernel in the global directory during application startup and in such cases reverting the kernel will not be possible).

9. Copy the newly extracted kernel to the global directory from the extracted path.
cp –pr * /sapmnt/<SID>/exe/uc/linuxx86_64

10. Once the kernel is copied, check the kernel version using the executable
“disp+work”.

11. Run the command ./saproot.sh <SID> with root user from the global directory. (This command
assigns the desired ownership and permissions to the executable such as br**,
sapuxusrechk, icmbnd etc.).

12. Once the checks are done we can start the SAP instance.

13. The SAP instance copies the kernel from the global mount-points to the local
mount-points and application directories using the back end program “sapcpe” to
all the application servers.

14. Once the instance is up and running, validate the kernel version from the
application layer as well.

Note:

1. Only the SAPEXE_***.***.SAR file is required when doing kernel upgrade
for a web-dispatcher or diagnostic agent.

2. The kernel is copied from the global directory to the local directories and
application specific directories which are as below.

Global: /sapmnt/<SID>/exe/uc/linuxx86_64
Local: /usr/sap/<SID>/SYS/exe/uc/linuxx86_64
Application: /usr/sap/<SID>/D**/exe

3. There may be situations when the kernel version is not reflecting at the
application layer, we may have to copy the executable manually to the local
directories and application specific directories

4. If the applied Kernel has compatibility issues with the OS kernel version or
SAP products installed, it can be traced out in the work directory logs. (This
happens only in cases when the compatibility is not checked in the product
availability matrix prior to doing the kernel upgrade).

5. There are other upgrades such as tp, igs.. and other executable which can
be explicitly upgraded in the same fashion as per the requirement or as a
workaround to the current problem being faced.