SAP Kernel Upgrade

                                                  SAP Kernel Upgrade on Windows Server

About the Kernel:

Kernel is the set of executables,  in kernel upgrade old executables are replaced by new set of executables.

SAP Kernel Resides in /sapmnt/<SID>/exe (or)

/usr/sap/<SID>/SYS/exe/UC/NTAMD64 for 64bit Machines

Kernel needs to be upgraded before support pack upgrade. 

We can check the Kernel Version by executing command
1) “disp+work” in cmd on Windows Environment   
2) SAP level go to the menu system-->status-->Shift+F5 

Objective :
Upgrade Kernel to Patch level 402.

Information:
Current Kernel Release :    720
Current Kernel Patch no:    300
Target Kernel Patch no  :   402 

Check the current Kernel Level

Check at SAP Level

Now download the kernel from marketplace
Login to service market place then follow the below navigation to download the kernel.

Download Database Independent and Database dependent .SAR file 

Two files will be downloaded

SAPEXE_40210007259.SAR and SAPEXEDB_40210007258.SAR

Shutdown the SAP Application server

Go to SAP MMC

In Kernel release 720 <SAPoscol>  OS service is not available

Now take the backup of old Sap executables (SAP Kernel). Backup The Kernel Directory for Rollback in any inconsistencies with the new kernel.

Uncar the kernel

Now replace the executables

 Kernel has been upgraded

Note:-  Kernel 720_rel patch level 401 instead of 402  
720 Kernel patch level 402 sap level on the SAP service marketplace is 402
Once installed however it shows patch level 401

Reason. 

Due to a critical security vulnerability in the SAP message server

(SAP note 1800603) Potential remote code execution.

SAP development had to replace the current stack kernel 720 with a new
version, PL#402, on service marketplace. Since only the SAP message
server was affected by the vulnerability and in order to minimize risks
of unwanted side-effects, they decided to replace only the SAP message
server within the corresponding archive.

Consequently all other executable files remained unchanged from the previous version, PL#401.
Especially disp+work from patch level 402 still shows it's version as
patch level 401. This is intended and normal behavior. 
( according to  http://wiki.scn.sap.com)

Now start the SAP system