What is the SAP kernel, and why should I care?

Please note: This blog was updated 15th July 2016 with the current information.  All content is believed to be accurate at the time of publishing, but may change without warning.  

The SAP kernel is the core component of any SAP system. It consists of the executable files that run on the server to handle connections to the system and execute the SAP programs. Using the latest stable kernel is vital to ensure your system runs smoothly.

How to check your kernel

Updating your SAP kernel is the responsibility of the basis team, but any user of an SAP system can check the kernel version to ensure they are keeping it up to date. Use the menu ‘System > Status’ to open this dialogue box:

The ‘Kernel release’ shows the release of your kernel and ‘Sup.pkg lvl.’ shows the support package.

Kernel Release Maintenance

It is important to use a kernel that is still under maintenance from SAP. If your kernel is not under maintenance, you will not get important updates or support from SAP. Running an unmaintained kernel may mean you need to do an urgent unplanned kernel update if you require support from SAP for any issue.

Kernel release

Maintenance ends

You should upgrade to

4.6C, 4.6D or lower

 

None - SAP upgrade required

700

31st August 2012

721 (downward compatible) or 722 (downward compatible) 

720 or 720_EXT

31st March 2015

721 (downward compatible) or 722 (downward compatible) 

721 or 721 EXT

31st December 2020

No upgrade required

722 or 722 EXT

31st December 2020

No upgrade required

740

31st July 2014

742 (downward compatible for NW 7.4 SP8+) 

741

30th June 2015

742 (downward compatible for NW 7.4 SP8+) 

742

31st March 2017

742 (downward compatible for NW 7.4 SP8+) 

745

31st August 2017

No upgrade required

 

The source for SAP maintenance end dates is the Product Availability Matrix (PAM).  The above table is correct at the time of writing based on the information in the PAM.

Choosing a Kernel Release: Downward Compatible Kernels

Your kernel release does not need to match your SAP product release version or NetWeaver release version.  For NetWeaver 7.0 to 7.3 you should use the 721 or 722 kernel, for NetWeaver 7.4 SP8+ you should use the 7.45 kernel, and for NetWeaver 7.4 SP2+ you should use the 7.42 kernel. 

It is important to check your system meets the requirements for the new kernel in the relevant SAP Note:

Innovation Kernel: What’s the difference between kernel 721 and 722?

Release 721 and 722 are maintained until 31st December 2020, so customers wonder what the difference is. 

Kernel 722 is the innovation kernel, meaning it will contain new functionality as it is developed, whilst 721 is the standard kernel.  You should consider using the 722 kernel only if you would like any of the functionality listed under ‘1. New Features’ in SAP Note 2133909

What are EXT kernels?

All SAP kernels are built on a specific version of the operating system and compiler.  When the operating system and compiler for a particular platform reaches the end of support, SAP will make a newer kernel with a newer version of the operating system and compiler called the EXT kernel. 

The EXT kernels for a particular release generally have slightly different compatibility, for example SQL Server 2005 is supported on a 722 kernel, but not the 722 EXT kernel. SQL Server 2014 is supported with the 722 EXT kernel, but not 722. 

It is recommended to use the newest (ie. EXT) kernel that is supported for your platform, as it is more likely to be created on a supported platform with a supported compiler.  More information on EXT kernels is available in SAP Note 1553300.

Kernel Support Package Level

As well as ensuring your kernel release is under maintenance, you should update your kernel at least once a year to the latest support package.  If the support package level is more than a year old, then you should raise it with your basis team.  This table shows the last few support package levels for current kernel releases at the time of writing, if yours is older you should definitely upgrade.  

Kernel Release

Support Package Level

Release Date

721

300

May 2014

400

December 2014

401

March 2015

402

March 2015

500

April 2015

600

October 2015

700

June 2016

722

4

May 2015

13

October 2015

101

March 2016

742

17

September 2014

28

November 2014

101

March 2015

200

July 2015

300

November 2015

400

April 2016

745

15

October 2015

20

November 2015

23

November 2015

100

March 2016

200

June 2016

 

How to Upgrade the Kernel

Kernels are upgraded by simply replacing the executable files on the server with the new versions.  The activity is performed by the basis team.  Kernels contain no business logic so there is limited risk, but minimal testing is required to ensure the system runs well afterwards. 

For our Managed Service customers we include the latest kernel alongside any support packages we apply, meaning the new kernel is also tested as part of the testing for the support package.

The direct impact of replacing the kernel is a restart of the SAP system, but there is the option of performing a rolling kernel switch to replace your kernels without downtime for a critical environment. 

Further Reading

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by Robert MacDonald, Senior SAP Consultant