msExchESEParamMaxSessions RRS feed

  • Question

  • Hello,

    Few days ago we had the following error on our Exchange system:

    No database session was available to satisfy a request on the mailbox database 'First Storage Group\Mailbox Database'.
     The number of sessions configured via the Active Directory attribute msExchESEParamMaxSessions on the storage group may be set too low for the level of activity on this storage group.
     The current value for this parameter is 329

    After a restart of the server the value down to 127.

    Since then, we have been monitoring the Database Session thourgh Perfmon and the value has increased to 145.  We suspect from a 3rd party software (backup, BES, antivirus) becasuse the increase occurs at night but we have not way to know which.

    Anyone knows how to discover wich process is leaving open sessions?

    We hace tried witch Exchange User Monitor without luck.


    Many thanks,

    Josep Lluís.



    Monday, November 28, 2011 9:41 AM


  • Hi 
       As far as I know, only Exmon can monitor session and the number of clients who connect to exchange through MAPI.
        This events occurs if MAPI sessions are very high & user activity are extremely high or if they use any 3rd party software’s like AV or Brick level backup that may cause the sudden increase in the MAPI sessions.
    Also take into account that BES services can stress a database. Example: Especially connecting the BES device via USB sync can kill an Exchange server .
       To resolve this error, do one or more of the following:


    Adjust the attributes identified in the Explanation section to increase the number of available database sessions.

    This the appropriate action we recommended to some customers.

    I would not adjust it to all stores, only stores that are referenced in the event 1164

    Increase the msExchESEParamMaxSessions from current 389 to 505


    In ADSIEdit:


    1. Expand Configuration container

    2. Expand Services container

    3. Expand Microsoft Exchange container

    4. Expand Exchange Organization container

    5. Expand Administrative Groups

    6. Expand the Administrative Group container where the server resides

    7. Expand the Databases container where the database resides

    8. Right click the database container where the database resides and select Properties

    9. Locate the msExchESEParamMaxSessions attribute and click Edit ( If not set it calculates the default in this case 389 )

    10. Enter the number 505 (increase the current value in the error message by 30% )


    • Marked as answer by Josep Mas Tuesday, November 29, 2011 3:16 PM
    Tuesday, November 29, 2011 8:54 AM