High CPU Usage (over load) w3wp.exe RRS feed

  • Question

  • Hello all,

    We were waiting for it so long and finally got the Go to upgrade our Exchange 2007 SP3 to Exchange 2016 (planned next December), I said that because I know our in-Premise messaging platform is out of support, nonetheless I hope I'd get some explanation concerning my case.

    The problem we are facing is here for around 2 years or more. After deep investigations, we figured out which process is causing the CPU spike on our CAS Server, which happen to be w3wp.exe (MSExchangeSyncAppPool). Rebooting the server or recycling this poll result in an immediate release of the CPU utilization of this process. But after a random time the load appears again, sometimes the spike would last hours and even days other times it would last minutes. The IIS logs don't show really unexpected or any relevant errorsn the users with most hits are not using iPhones or iPads and are actually updated to recent Android versions.

    The CAS Servers are configured to use their IP + the NLB Virtual IP address which is mapped to the Internet Name In normal circumstances, all traffic should be handled by the VIP of the CAS and distributed equally to both CAS servers.

    The issue is that all the traffic is being submitted unfairly to one CAS and so overload its CPU while the other one is completely normal and not stressed at all.

    We know that the WNLB can't distribute CPU and Memory load across the cluster nodes and we are not to do so, but how it does for the ActiveSyc which is after all a web App?

    My concern is to understand how the Windows NLB (WNLB) really handles the ActiveSync requests? and which settings should be adjusted to distribute traffic equally across both CAS servers?

    Our environnement is :
    2 CAS (in NLB)  
    2 HUB
    2 MBX Nodes (in CCR)
    All running Windows 2008 Server SP 2 (version 6.0)

    Any help is much appreciated.

    Thanks in advance.


    Tuesday, July 10, 2018 10:14 AM

All replies

  • So does your NAT or firewall preserve the source address of the clients?  If not, everything looks like it's coming from the same address and will be handled by the same CAS.

    Ed Crowley MVP "There are seldom good technological solutions to behavioral problems."
    Celebrating 20 years of providing Exchange peer support!

    Tuesday, July 10, 2018 11:44 PM
  • Hello Ed,

    Thanks for the reply and sorry for the delay.

    Yes our NAT equipement keeps the source address of the clients. 

    I am clueless.


    Thursday, July 12, 2018 3:15 PM