kernel-azure on PAYG images is not supported for running SAP applications

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Environment

SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server 12

Situation

The release of SLES 15 included also a new kernel build, kernel-azure, which is the default only for SLES PAYG and SLES HPC PAYG images. The benefit of using kernel-azure is that it will incorporate new features from Azure that need Linux kernel support faster than the kernel-default build. However it has some major drawbacks:

It breaks kABI (Kernel Application Binary Interface). Please note that SUSE is very strict on guaranteeing kABI stability/compatibility on Service Pack cycle.
kernel-azure build has no long term support (LTSS) , i.e. it gets full support until EOL of the given service pack according to the overlap lifecycle.
kernel-azure is a stripped off kernel, as it missed some modules that are available on the SUSE default kernel.
There is no support for add-on products such as HA or Kernel Live Patching for PAYG on-demand instances.

SAP applications are tested and certified using a stable kABI, only on SUSE default kernels. For all those reasons, especially the potential kABI breakage/compatibility, as also referenced on SAP Note 3123142, kernel-azure is not supported for running SAP applications.

Resolution

For SAP applications running on PAYG on-demand instances it is important to switch from kernel-azure to kernel-default (which is included on PAYG images as well):

# zypper in –no-recommends kernel-default
# zypper rm kernel-azure
# shutdown -r now

The use of –no-recommends option prevents the auto-installation of the kernel-firmware package which is not needed inside a VM.

Cause

In order to incorporate new features from Azure that need Linux kernel support faster than the kernel-default build, SUSE has lifted the kABI restriction for the custom-tuned kernel-azure. Due to the lifting of the kABI restriction and potential breakage, kernel-azure package is not in SUSE Linux Enterprise Server for SAP Applications images and should not be installed on running instances from those images as it breaks the SAP certification criteria. SAP applications have only been tested and certified on stable kABI.

Status

Reported to Engineering

Additional Information

Further information can be found on:

A Different Builtin Kernel For Azure On-Demand Images
SAP Note 3123142 - Microsoft Azure - Change SLES Kernel from azure to default
SUSE and Microsoft Collaborate to Deliver First Enterprise Linux Kernel Optimized for Azure

Disclaimer

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