Hi
For Oracle databases running on AIX, configuring this parameter is a key performance tuning practice, especially in a Real Application Clusters (RAC) environment.
Best practices for vpm_xvcpus
- Set the value to 2: Oracle and IBM strongly recommend setting vpm_xvcpus=2 for Oracle database workloads on AIX with processor folding enabled.
- Reasoning: A value of 0 (the default) indicates that the Virtual Processor Manager can fold or disable virtual processors when it determines they are not needed. This can cause performance problems and even RAC node evictions during light loads, as VPM might fold too many virtual processors. Setting vpm_xvcpus=2 keeps a minimum of two additional virtual processors unfolded and ready to handle workload spikes, improving stability and performance.
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Anas AlSaleh
IBM Power Systems Software Specialist
Saudi Business Machines ( SBM )
Riyadh
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Original Message:
Sent: Thu September 25, 2025 11:12 PM
From: CHRISTOPHER WICKREMASINGHE
Subject: What is the best practices for parameter vpm_xvcpus for Oracle RAC 19c?
Hi Duy
For RAC the suggested/minimum is vpm_xvcpus=2. Going higher might have a negative impact.
Refer the power10 doc at https://community.ibm.com/community/user/viewdocument/aix-with-oracle-database-on-ibm-pow?CommunityKey=daa942cb-b783-4fd3-ba27-a2d7462f9530&tab=librarydocuments
HTH, Chris
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Chris Wickremasinghe
IBM
Original Message:
Sent: Thu September 25, 2025 12:35 AM
From: DUY NGUYEN SI
Subject: What is the best practices for parameter vpm_xvcpus for Oracle RAC 19c?
Dear all,
My company is using POWER10 S1024 running AIX 7.2 with Oracle RAC 19c. I seek advice for Oracle best practices with the parameter vpm_xvcpus setting:
Is it set to the number of vCPUs? Our server has 16 physical cores. Thanks in advance!
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DUY NGUYEN SI
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