On the APM CE (CEM) Defect Time Distribution Graph, the data points are far less than the number of total transactions.

Document ID : KB000019317
Last Modified Date : 14/02/2018
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Description:

This explains the differences between data points and transactions and why there could be a sizable difference. This supplements TEC596465.

Solution:

To explain the difference, we need to define transaction and data points.

  • A Transaction is either successful or a defect. This means it has a known response time and size.

  • Data Points represent the number of Transactions where APM CE has seen both the request and response completely within the connection timeout boundary, they are not marked as defective, and provide Time and Size information.

Some users have reported situations where the number of Data Points is half the number of Transactions. Such large discrepancies in data/transaction counts can be caused by:

  • Wrong transaction configuration: This can be due to recording while the wrong span port configuration was active, incurring duplicate traffic and/or broken traffic, or the wrong session identifier was setup.

  • The transaction definition is not specific enough. Another parameter may need to be matched.

  • Bad SPAN/Mirror traffic.

Note that a combination of unclean data and incorrect session identifiers will lead to unpredictable results. One example would be binding components of different users issuing requests from the same IP, such as could happen through NAT internet access, to the same transaction.

Supplement to TEC596465