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Exchange Throttling Policies - What does EwsCutoffBalance really mean?

    Question


  • I'm try to figure out how throttling policies affect EWS.

    For EWS, we have these values:

    • EWSMaxSubscription: the number of active subscriptions done by the user.
    • EWSMaxConcurrency: how many concurrent connections or actions a single client may take.
    • EwsMaxBurst: how far above the standard resource limit a client may go in shorts bursts (in milliseconds). It probably comes into effect when the percentage of CPU/Memory usage by Exchange exceeds the defined threshold (depending of the setup, I suppose).
    • EwsRechargeRate: the speed at which the user’s resource budget recharges or refills (in milliseconds).

    I understand each of the above throttling parameters. However, I'm not sure to clearly understand the EwsCutoffBalance. This parameter defines the resource consumption limits for EWS user before that user is completely blocked from performing operations on a specific component...

    My questions...

    1. How this value is used regarding the EwsMaxBurst and the EwsRechargeRate values?
    2. What is the unit of this parameter?
    3. How can we determine the right value if I need to change the throttling policy of a specific user account (instead of using "Unlimited")?
    Monday, July 25, 2016 2:28 AM

Answers

  • Hi, 

    For your questions, please see below:

    1.    Per my understanding, the EwsMaxBurst specifies the amount of time that an EWS user can consume an elevated amount of resources before being throttled, when the resources is throttled, it will Recharge , the parameter EwsRechargeRate control the rate.  And the parameter specifies the resources consumption limits, means that it’s the whole resources for an EWS user before that user is completely blocked from performing operations on a specific component.

            Usually, the value of EwsMaxBurst is less than the value of EwsRechargeRate. And the value of EwsCutoffBalance is larger than the those two values. They are not so closely linked.
                  
    2.    It has no unit it’s a limit;
    3.    Please refer to the following values in the below Table:

           

    Recommended Throttle Policy Settings on Exchange Server 2013

    Parameter

    Recommended Configuration Value — Exchange Server 2013

    EwsCutoffBalance

    3000000

    EwsMaxBurst

    300000

    EwsMaxConcurrency

    100

    EwsMaxSubscriptions

    Unlimited

    EwsRechargeRate

    900000

    These are the only EWS parameters that can be changed in Exchange Server 2013.

     

    Hope it helps.

    Best regards,


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    Tuesday, July 26, 2016 9:25 AM
    Moderator