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Performance Impact of RAC Interconnect Traffic

Avatar photoCustomer Questions & Answers 5 replies

We run Oracle EBS on a Real Application Clusters (RAC) environment and suspect high inter-instance traffic might be slowing us down. How can I use Blitz Report to analyze the usage of the interconnect device by instance?

5 replies

  • Support Enginatics

    You should use the DBA AWR Interconnect Traffic report. This report displays information about interconnect usage by instance in a RAC configuration.

  • Avatar photoCustomer

    What are the key categories of traffic measured in this report that I should look for?

  • Support Enginatics

    The key categories displayed are `ipq` (Parallel query communications), `dlm` (Database lock management), and `cache` (Global cache communications). Other values are typically internal to Oracle and not expected to have high usage.

  • Avatar photoCustomer

    If cache traffic is high, what does that usually indicate?

  • Support Enginatics

    High `cache` traffic indicates frequent global cache communications, often implying that buffer blocks are being transferred frequently between instances. This may point toward poor data locality or insufficient buffer cache sizing.

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