Exchange 2016 resources and constant MSExchangeAutodiscoverAppPool restarts

Anonymous
2021-07-13T17:26:09.237+00:00

Hello, I'm running into an issue where I have to constantly restart the MSExchangeAutodiscoverAppPool. Otherwise after mailbox moves from an old Exchange 2010 server, the Outlook client won't reconnect to the newly moved mailbox.

Aside from the old Exchange server which will be uninstalled as soon as we're migrated, this is a single server instance of Exchange 2016 CU20. There are two mailbox databases containing a total of 850 mailboxes pretty evenly spread between them. About 1Tb of mailbox data in total. There are 6 CPUs allocated to the box which seems to be adequate, but 20Gb RAM. The box always seems to run at about 95% RAM utilization, each Store.Worker.exe process consuming about 1.8Gb.

I've managed Exchange for many years through many different versions and memory sizing always seems like a difficult topic for Exchange. The sizing spreadsheet out there is sort of a joke, or maybe I am just too dense to follow it. Anyway, in my experience a mailbox Exchange server will consume as much RAM as you give it. Period. You run perfmon and it will say you are experiencing excessive paging, add RAM. Always no matter what.

So all that said, I am wondering based on the details above if my AppPool problem is just a bug in this build of Exchange or if maybe I should add some RAM to this Exchange server. Thoughts or suggestions from someone who knows more than I would be appreciated. Thank you.

Regards,
Adam Tyler

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Kael Yao-MSFT 37,496 Reputation points Microsoft Vendor
    2021-07-14T03:06:19.603+00:00

    Hi Adam.

    Anyway, in my experience a mailbox Exchange server will consume as much RAM as you give it.

    Yes. It is by design.

    I am wondering based on the details above if my AppPool problem is just a bug in this build of Exchange or if maybe I should add some RAM to this Exchange server.

    I found this Microsoft KB about this issue for your reference: Outlook logon fails after mailbox moves from Exchange 2010 to Exchange 2013 or Exchange 2016

    The cause is due to Autodiscover:
    After the mailbox move is completed, Exchange Server 2013 or 2016 continues to proxy the autodiscover request to Exchange Server 2010.
    Exchange Server 2010 responds with a 302 redirect back to Exchange Server 2013 or 2016 (depending on the upgrade).

    And the solution is to restart the Autodiscover Application Pool on Exchange 2016.

    So I suppose you may need to restart the Autodiscover Application Pool if you would like to ensure newly migrated mailboxes can be connected by Outlook.

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