ADCS sessions

Question

In ADCS on Windows 2008R2 we are getting " An attempt was made to open a Certification Authority database session, but there are already too many active sessions" on a request using
CERTADMINLib.IEnumCERTVIEWROW.Next(). I found a recommendation to set
HKLM\SYSTEM\CurrentControlSet\Services\CertSvc\Configuration\DBSessionCount to 64 hex (100 Dec).  With this set we could only get 10 sessions open using IEnumCERTVIEWROW. With debugging and logging turned on I found a reference to DBMaxReadSessionCount 
and a matching reference in certsrv.h. When HKLM\SYSTEM\CurrentControlSet\Services\CertSvc\Configuration\DBMaxReadSessionCount  is also set to 64 hex (100 Dec) we can get 100 session running.
What is the impact of setting DBMaxReadSessionCount and are there any problems with explicitly setting this value?
Dan

Answer 1

Hi,
Thanks for your post.
The registry key "DBSessionCount" is used for controling the number of concurrent sessions to the certificates database that can be made. But the registry key "DBMaxReadSessionCount" is used to dicatate the number of sessions.
In the case where DBMaxReadSessionCount is not present, that value is calculated by taking DBSessionCount and dividing it by 10. Please refer to the articles as below for more information:
How CA Certificates Work
http://technet.microsoft.com/en-us/library/cc737264(v=ws.10).aspx
Troubleshooting (Certificate Autoenrollment in Windows Server 2003)
http://technet.microsoft.com/en-us/library/cc755801(v=WS.10).aspx
Certificate Services Tools and Settings
http://technet.microsoft.com/en-us/library/cc780742(v=ws.10).aspx
Hope the information above is helpful to you. If you have any questions or additional information, please feel free to let me know. 
Best regards,
Ann
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