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SAP Performance drops after AIX upgrade

By Wera Stoeckel posted Fri December 11, 2020 12:19 PM


Several AIX service packs  contain a "sensitivity" against incorrectly  configured fiber channel (FC) devices.
When FC devices are not correctly mapped from VIOS to
the AIX LPAR then certain commands like 'fcstat' or the 'uuid_create' API call may be delayed by around 20-30 seconds until returning.
Since the SAP kernel makes extensive use of UUIDs, these delays can lead to an effectively unusable SAP system.

Update (2022-05-20): The issue is documented in the IBM APARs IJ37424 and IJ30105 and fixes are available for AIX 7.1 TL5 and AIX 7.2 TL4. For AIX levels without fix support - e.g. AIX 7.2 TL3 - the issue can be avoided by ensuring proper mapping of FC devices between VIOS and LPAR. For more details see SAP Notes 2267287 - Using SAP systems with AIX 7.2 and 1541935 - Using SAP systems with AIX 7.1.

2020-03-31 by Ralf Kokowski, updated 2022-05-20 by Harald Duvenbeck