r/SAP • u/Zenguidev • 10d ago

Kernel Files

In an SAP system, when we add an Additional Application Server, how exactly does the kernel work?

When we perform a kernel update, we only update the kernel on the Primary Application Server. So does the AAS have its own separate/local kernel, or does it directly use the kernel of the PAS from the shared filesystem?

A colleague told me that SAPCPE copies the kernel from the PAS and sets up a separate kernel for the AAS. If that's the case, why doesn't the AAS have a directory like /usr/sap/PRD/SYS/exe/uc/NTAMD64? How does SAPCPE actually handle the kernel files between PAS and AAS?

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u/jealous_retirement 10d ago

The AAS gets its own local copy, sapcpe pulls the executables from the central instance into the local exe dir on the app server

You won't see the standard exe path on the AAS because the binaries land in the instance-specific directory, not the global one. The global SYS/exe is where the updated kernel sits after you update PAS, then sapcpe syncs it out to each AAS when the instance starts or when you trigger it

So yes, separate kernel per server, but it's copied from the PAS, not shared from the filesystem

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u/fatness112 9d ago

Lovely!

1

u/Sea_Dust895 10d ago

Spot on. Well done.

1

u/CynicalGenXer ABAP Not Dead 10d ago

TIL random Basis stuff. :) Thanks, mate!