SAP on AIX
Find information, blog posts, and useful resources for running your SAP system on the IBM operating system AIX.
AIX Active Memory Expansion (AME) is a unique feature of the AIX operating system. It allows you to "expand" your available memory without adding real memory to the system. Check out this white paper which shows the result of performance measurements with the SAP SD benchmark workload and gives recommendations how to optimally configure AME:
You want to avoid costly SAP downtimes when updating your AIX server to newer technology levels or service packs? Check out the Live Update functionality on AIX:
For details refer to the White Paper from IBM which validated the AIX Live Update capability in an SAP landscape.
An update to the well-known Best Practices guide has been published by IBM. This version concentrates purely on SAP on AIX and contains up-to-date information about how to optimally utilize and configure AIX and PowerVM for SAP.
Link to IBM WhitepaperWith IBM AIX 7.2 TL 2, the AIX operating system supports the new communication protocol solution SMC-R. This IBM white paper demonstrates and summarizes the benefits of using SMC-R in a distributed SAP on AIX environment.
Link to IBM White Paper
SAP kernel 793 on AIX released for S/4HANA 2023
SAP kernel 793 on AIX is released for S/4HANA 2023 - see SAP Note 3372947.
Before installing the new kernel, make sure you read SAP Note 1780629 - AIX: Minimal OS Requirements for SAP Kernel and update your system to the AIX level and the C++ runtime level that are required to run this kernel. On AIX, SAP kernel 793 is built using the IBM Open XL C/C++ for AIX 17.1.1 compiler which supports advanced C++ language features. These features are only supported on POWER8 or newer IBM POWER servers.
SAP kernel 793 on AIX comes with built-in 64K page size support. Especially if you did not use 64K pages with earlier kernel releases, you should see a performance improvement. For more information see SAP Note 3385801.

SAP kernel 754 with improved performance on AIX
SAP Kernel 754 is released as downward compatible kernel for older kernels 740 up to 753 (see SAP Note 3156866). On AIX, this kernel was built with a newer compiler which is able to exploit current IBM POWER processor instructions. As a result, you can expect to see performance improvements compared to 753 or earlier kernels in particular when running the kernel on POWER9 or POWER10 servers. Furthermore, kernel 754 on AIX comes with built-in 64K page size support. Especially if you did not use 64K pages with earlier kernel releases, you should see a nice additional performance boost. Please note that in order to switch to 754 kernel you should first update your server to the required AIX and C++ runtime levels. (see SAP Note 1780629). Consider using AIX Live Kernel Update to avoid the downtime that would otherwise be associated with the AIX update.
SAP Note 3156866 - Using Kernel 7.54 instead of Kernel 7.40, 7.41, 7.42, 7.45, 7.49 or 7.53SAP Note 1780629 - AIX: Minimal OS Requirements for SAP Kernel

Active Memory Expansion now supported for 64K page sizes
Active Memory Expansion (AME) is a feature that allows AIX to utilize more memory than the configured real memory. AME uses hardware-accelerated memory compression to achieve this. In the past, AME only supported 4K memory pages and was also only supported for SAP with 4K page sizes. 64K page size support in AME has been available in AIX since AIX 7.1 and POWER8 servers. Now, this option is also available and supported for SAP. The 64K variant of AME is highly recommended. Tests with SAP workload have shown that it offers significant advantages compared to the 4K variant. For more details see the SAP Note 1464605 which was updated to include 64K page sizes.
1464605 - Active Memory Expansion (AME)How to properly size paging space and physical memory
When your AIX server runs into low memory or low paging space situations this can lead to an outage of your SAP system. Therefore, you should try hard to avoid these scenarios. SAP Note 1121904 will help you to properly configure both memory and paging space.
SAP Note 1121904 - SAP on AIX: Paging space and physical memory resources
How to avoid out of memory situations
Running out of virtual memory on your SAP application server is something you definitely want to avoid. Check out this SAP note which contains valuable hints and tips and best practices how to accomplish this. Learn about the SAP Host Agent metric OS.PercentPSBelowSigdanger which allows you to set an alert before your application server runs into problems.
SAP Note 2630086 - Avoid signal 33, out of memory on AIX