FIX: Denial of Services During Connections (248829)

SYMPTOMS

When a user connects from a remote site, sometimes due to network latency problem, the OLAP server enters a state where it cannot correctly recognize any of the incoming connection requests from client computers (even when there is no more network latency). The OLAP Server still responds to the queries from the existing connections while in this state.

If a user encounters this problem, he/she may see the following error message when connecting from OLAP Manager:

Cannot open connection to OLAP server 'ServerName'.

Or, he/she may see this when connecting from the MDX sample application:

Unable to open connection.
OLAP server error: The operation requested failed due to network problems.

RESOLUTION

To resolve this problem, obtain the latest service pack for SQL Server 7.0. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

301511 INF: How to Obtain the Latest SQL Server 7.0 Service Pack

Hotfix

The English version of this fix should have the following file attributes or later:

   Date         Time     Version      Size    File name     Platform
   -----------------------------------------------------------------
   11-Sep-2000  14:13    7.0.0.1464   933 KB  Msmdsrv.exe   Intel

NOTE: This hotfix requires service pack 2 (SP2) of Microsoft OLAP Services 7.0 in order to work properly. You can download SP2 from the following Web address:

http://www.microsoft.com/sql/downloads/sp2.asp

STATUS

Microsoft has confirmed this to be a problem in SQL Server 7.0. This problem has been corrected in U.S. Service Pack 3 for Microsoft SQL Server 7.0. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

274799 INF: How to Obtain Service Pack 3 for Microsoft SQL Server 7.0 and Microsoft Data Engine (MSDE) 1.0

For more information, contact your primary support provider.

This is not an issue with SQL Server 2000 Analysis Services.

MORE INFORMATION

When the OLAP Server gets into this state after all existing connections are closed, nobody is able to connect. To check whether you are running into this problem, you can run the following at the command prompt on the server computer and check the status of TCP connections on ports 2393 and 2394:

netstat -a

If you see half bound sockets, or sockets in the CLOSE_WAIT or TIME_WAIT state, then there is a high probability that this is the same problem.

It is difficult to describe exactly when such a situation may happen. However, there is a higher probability of running into this if the users are connecting over moderately slow network links (slower then T1, but faster then a 56K modem).