F5 load balancer recommendations for use with Clarity.

Document ID : KB000049575
Last Modified Date : 14/02/2018
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The following are recommended settings for use when using an F5 load balancer in front of Clarity application servers.


F5 Load balancer settings for Clarity

Persistence settings

  1. Set persistence timeout to slightly higher than the clarity session timeout (if clarity timeout = 60 min, set LB persistence timeout to 65 minutes)

    This will ensure that user requests are pinned to the same Clarity app server for the duration of the session.

TCP profile settings

  1. Set Zero Window Timeout to "indefinite" instead of the default of 20000 milliseconds.

    This setting affects long running HTTP requests, mostly from schedulers (OWB & MSP). After multiple "zero TCP window" packets from the clarity server, the F5 will terminate the socket and cause all sorts of issues with the schedulers when they are trying to save projects. Setting this to "indefinite" eliminates the zero window timeout issue (used with several large customers to solve their F5/OWB/MSP issues).

  2. Set the "Idle Timeout" in the TCP profile to a value sufficient to handle the largest end-user request, whether this is a request from OWB, MSP, XOG or an immediate report request. I recommend a minimum of 900 seconds (15 minutes) to allow Clarity to handle immediate report requests up to 10 minutes long. After 10 minutes, Clarity will return an error message to the end-user regarding immediate reports taking too long. An idle timeout shorter than 10 minutes will result in a LB timeout error instead of the nicely formatted Clarity specific error.