Microsoft KB Archive/168717

= SNA Server Performance Degrades if NT Domain Controller Down =

Article ID: 168717

Article Last Modified on 6/29/2004

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APPLIES TO


 * Microsoft SNA Server 2.0, when used with:
 * Microsoft Windows NT 4.0
 * Microsoft SNA Server 2.1, when used with:
 * Microsoft Windows NT 4.0
 * Microsoft SNA Server 3.0, when used with:
 * Microsoft Windows NT 4.0
 * Microsoft SNA Server 2.11 Service Pack 1, when used with:
 * Microsoft Windows NT 4.0
 * Microsoft SNA Server 2.11 Service Pack 2, when used with:
 * Microsoft Windows NT 4.0
 * Microsoft SNA Server 3.0 Service Pack 4, when used with:
 * Microsoft Windows NT 4.0
 * Microsoft SNA Server 4.0, when used with:
 * Microsoft Windows NT 4.0

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This article was previously published under Q168717





SYMPTOMS
Users with active 3270 or LU6.2 sessions through SNA Server may unexpectedly observe degraded host or AS/400 response time. This problem can occur when new users attempt to open sessions to SNA Server and a domain controller (or trusted domain controller) from the user's domain is unavailable to process user logon requests.



CAUSE
When a new user connects to SNA Server, the SNA Server logs the user on to Windows NT, causing Windows NT to perform user logon validation against a domain controller in the user's domain. If the domain controller cannot be reached (for example, due to a transient network problem), currently connected clients can experience intermittent response time delays.



WORKAROUND
To work around this problem, do one of the following:
 * Identify and correct the underlying cause of the slow or failed access to the trusted domain controllers.

-OR-
 * Break the Windows NT trust relationship with these trusted user domains, and configure the SNA Server clients to connect to the SNA Server computers using the Windows NT Guest account. This is only an option if all SNA clients have the same access requirements. For example, if all users are accessing the same 3270 LU pooled resources, or there is no defaulting of APPC LU's to users or groups. If this workaround is used, note that the Guest account is disabled by default within Windows NT User Manager, and must be manually enabled. Even though the Guest account is enabled, access to any Windows NT resources can still be prevented for guests, to allow access for SNA Server client use only.



STATUS
Microsoft has confirmed this to be a problem in SNA Server 2.11 (all service packs), 3.0 and 3.0 Service Pack 1 (SP1).

This problem was corrected in the latest SNA Server version 3.0 U.S. Service Pack. For information on obtaining this Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K



MORE INFORMATION
A fix to SNA Server 3.0 (post Service Pack 1) is available to correct this problem. With this fix applied, the SNA Server no longer handles client logon requests within an SNA Server DMOD critical section, and now processes logons asynchronously via other process threads.

Keywords: kbbug kbfix kbnetwork KB168717

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